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Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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71 | P a g e  

EFFECT OF SUSTAINABLE LEAN SIX SIGMA ON OPERATIONAL 

EFFICIENCY IN SOUTHEAST NIGERIA'S FOOD INDUSTRY 
 

1Obodoagu, Kenneth Ogomegbunam (Ph.D), 2Cyril Anamelechi Chiana 

(PhD) and 3Okechukwu, Elizabeth Uzoamaka (PhD) 
1Department of Business Management, Godfrey Okoye University, Enugu 

2Department of Marketing, Abia State University, Uturu 
3Department of Business Administration, Enugu State University of Science and Technology 

DOI: https://doi.org/10.5281/zenodo.15878437 

 

Abstract: The study examined the effect of Sustainable Lean Six Sigma on operational efficiency in 

Southeast Nigeria's food industry. The specific objectives were to; evaluate the effect of the continuous 

improvement process on the operational efficiency and identify the effect of eliminating waste on 

operational efficiency in Southeast Nigeria's food industry. A survey research design was selected for 

the investigation. A standardized questionnaire with a point Likert scale was used to collect data for 

the study. The data was analyzed using the mean, standard deviation, and fundamental percentages. 

(SPSS version 20, a program for descriptive statistics). The result review that Continuous 

improvement process has a significant positive effect on the operational efficiency with the calculated 

Z- value of 7.098 < 10.089 against the critical Z- value of .000. while Eliminating waste has a 

significant positive effect on operational efficiency with the calculated Z- value of 7.117 < 11.160 

against the critical Z- value of .000 in Southeast Nigeria's food industry. 

Keywords: Efficiency, Lean, Operational, Sigma, Six 

 

  

1.1 Introduction 

In today's increasingly interconnected and environmentally conscious world, organizations face 

mounting pressure to optimize their operations while minimizing their environmental and social 

impact (Abubakar & Igbokwe, 2022; Uche, 2024). This dual challenge has spurred the rise of 

Sustainable Lean Six Sigma (SLSS). This powerful integrated methodology combines the process 

improvement principles of Lean Six Sigma with the goals of sustainability, providing effective solutions 

to those dual challenges organizations face. It is opined that Sustainable Lean Six Sigma provides a 

comprehensive approach to enhancing organizational performance, minimizing waste, and promoting 

environmental and social responsibility (Ajayi, 2023). To appreciate the significance of Sustainable 

Lean Six Sigma, it is essential to understand its constituent methodologies, which Originated from 

Toyota's production system, Lean focuses on eliminating waste ("muda" in Japanese) in all its forms, 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

Email: contact@americaserial.com 
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72 | P a g e  

including defects, overproduction, waiting, non-utilized talent, transportation, inventory, motion, and 

extra processing. By streamlining processes and improving efficiency, Lean aims to deliver maximum 

value to customers with minimal resource consumption (Chinedu, 2023; Eze, 2023; Ndukwe, 2023). 

In the context of business, sustainability encompasses environmental, social, and economic 

dimensions, often referred to as the "triple bottom line." It involves minimizing environmental impact 

through resource conservation, pollution prevention, and waste reduction; promoting social equity 

through fair labour practices, community engagement, and ethical sourcing; and ensuring long-term 

economic viability through efficient operations and responsible financial management (Chinedu, 2023; 

Eze, 2023). 

Operational efficiency refers to the ability of an organization to deliver goods or services with minimal 

waste of resources, including time, materials, energy, and human effort (Okafor, 2022).  In the context 

of SLSS, operational efficiency is not solely focused on cost reduction and output maximization but also 

on minimizing environmental impact and promoting social well-being (Nwankwo & Chukwu, 2024).  

This broader perspective requires a shift in mindset, where efficiency gains are evaluated in terms of 

their overall contribution to the "triple bottom line": economic, environmental, and social performance 

(Okwudili, 2024). 

Southeast Nigeria's food industry is a critical sector for economic growth and development, 

contributing significantly to the region's GDP and employment. However, the industry grapples with 

inefficiencies, high levels of waste, and environmental degradation due to unsustainable practices (Obi, 

2024). According to recent reports, the region's food supply chain is often characterized by inadequate 

infrastructure, poor logistics, and limited access to modern technologies, leading to high rates of 

spoilage and waste (Oko, 2023). These challenges necessitate innovative solutions to enhance 

operational efficiency and promote sustainability. 

1.2 Statement of the Problem 

The food industry in Southeast Nigeria is critical to the region's economic growth, yet it faces significant 

challenges related to operational inefficiency, high levels of waste, and sustainability concerns. Despite 

the potential benefits of Sustainable Lean Six Sigma (SLSS) in enhancing operational efficiency, many 

food manufacturers in this region have not fully adopted or implemented these practices. This gap 

results in suboptimal resource utilization, increased costs, and a negative environmental impact, 

ultimately hindering the industry's competitiveness and sustainability. 

Specifically, the lack of streamlined processes and inadequate waste reduction strategies contributes to 

substantial food spoilage and inefficiencies throughout the supply chain. Additionally, cultural 

resistance to change and insufficient training further impede the adoption of SLSS methodologies. As 

a result, the operational efficiency of food manufacturers in Southeast Nigeria remains below potential, 

adversely affecting not only their profitability but also their ability to contribute to regional economic 

development and environmental sustainability. 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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This study aims to investigate the effects of Sustainable Lean Six Sigma on operational efficiency within 

Southeast Nigeria's food industry, identifying barriers to implementation and proposing actionable 

strategies for enhancing both economic and environmental performance. 

1.3 Objective of the study  

The main objective of this study is to examine the effect of Sustainable Lean Six Sigma on operational 

efficiency in Southeast Nigeria's food industry. The specific objectives were to; 

i. Evaluate the effect of the continuous improvement process on the operational efficiency in 

Southeast Nigeria's food industry. 

ii. Identify the effect of eliminating waste on operational efficiency in Southeast Nigeria's food 

industry. 

1.4 Hypotheses of the study 

i. The Continuous improvement process has no significant effect on the operational efficiency in 

Southeast Nigeria's food industry. 

ii. Eliminating waste has no significant effect on operational efficiency in Southeast Nigeria's food 

industry. 

Literature Review 

2.1 Conceptual Review 

Sustainable Lean Six Sigma  

In recent years, Lean Six Sigma (LSS) has drawn significant attention for its ability to improve 

environmental performance and encourage sustainable manufacturing practices (Zhang, Luo, & 

Skitmore, 2015; Ganjavi & Fazlollahtabar, 2021). LSS is an approach that reduces waste and errors in 

business processes by combining Six Sigma quality management with Lean manufacturing principles. 

However, by implementing strategies like energy efficiency, waste reduction, and the utilization of 

renewable resources, sustainable manufacturing practices seek to lessen the adverse effects of 

production on the environment (Antony, Snee, Hoerl, & Management, 2017). Analyzing the connection 

between LSS principles, data-driven decision-making, and environmental performance within the 

framework of sustainable manufacturing practices is the goal of this review of the literature. Relevant 

keywords and search terms, including "Lean Six Sigma," "sustainable manufacturing," "environmental 

performance," and "data-driven decision making," were used to search academic databases and other 

sources in order to obtain a wide range of literature on the subject (Huang et al, 2023).  

The review will then synthesize and analyze the literature to determine the critical elements that 

support the effective application of LSS in advancing sustainable manufacturing practices and 

enhancing environmental performance. Through an analysis of the literature, the review seeks to offer 

insights and suggestions for manufacturing firms looking to enhance their environmental sustainability 

while preserving operational effectiveness and profitability (Huang et al, 2023). The body of research 

on LSS in sustainable manufacturing practices and its impact on environmental performance provides 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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74 | P a g e  

us with useful data and case studies. But additional research is required to understand the particular 

issues that arise when LSS is applied to sustainable production (Huang et al, 2023).  

The advantages and effective applications of LSS for sustainable manufacturing have received more 

attention in the literature than the possible drawbacks and restrictions of this approach. Furthermore, 

not many studies look at the combination of data-driven methods and LSS concepts to enhance 

environmental performance. More research is required to determine how data-driven decision-making 

might improve LSS's ability to support environmentally friendly production methods and sustainable 

manufacturing practices, even if some studies have examined how data science fits into LSS and how it 

impacts various industries (Huang et al, 2023). Future studies could examine the particular issues that 

come up when using LSS in environmentally friendly production and how they might be resolved. It 

would be advantageous to investigate the ways in which LSS concepts and data-driven approaches 

complement one another to enhance environmental performance in various businesses. This would 

increase our understanding of the subject and provide industry professionals with the resources they 

need to advance sustainable manufacturing methods. 

Continuous Improvement (CI) 

Continuous Improvement (CI), also known as Kaizen (Japanese for "change for the better"), is a 

fundamental management philosophy that emphasizes ongoing efforts to enhance products, services, 

or processes (Bessant, & Maher, 2009, Suárez-Barraza et al 2012). It is not a one-time project but a 

sustained, incremental approach to improvement, involving all members of an organization (Liker, 

2004, Jørgensen, et al 2003). The core idea is that small, consistent changes can lead to significant 

cumulative improvements over time (Bessant, & Maher, 2009, Suárez-Barraza et al 2012). 

Understanding and meeting customer needs and expectations is central to continuous improvement 

(Deming, 2000, Oakland, 2014). Improvements are driven by customer feedback and the desire to 

enhance customer satisfaction (Deming, 2000, Oakland, 2014). Continuous Improvement focuses on 

improving processes rather than individual performance (Bessant, & Maher, 2009, Suárez-Barraza et 

al 2012, Tortorella, & Fettermann, 2018). By analyzing and optimizing processes, organizations can 

eliminate waste, reduce errors, and improve efficiency (Bessant, & Maher, 2009, Suárez-Barraza et al 

2012, Siriram, 2019). 

Eliminating Waste 

Waste elimination is a multifaceted concept gaining increasing importance across various sectors, 

driven by concerns about resource depletion, environmental degradation, and economic efficiency. This 

review explores the conceptual underpinnings of waste elimination, examining its evolution, diverse 

applications, and strategies for effective implementation. Waste, broadly defined as any resource that 

is not utilized optimally, presents a significant challenge to sustainability. Eliminating waste requires a 

shift towards circular economy models, emphasizing reduction, reuse, recycling, and recovery. The 

concept of waste elimination has evolved significantly over time. Initially rooted in manufacturing and 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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75 | P a g e  

operations management, the principles have expanded to encompass broader societal and 

environmental contexts. Taiichi Ohno's work at Toyota pioneered the concept of "Muda" or waste, 

categorizing it into seven types: overproduction, inventory, defects, motion, waiting, transportation, 

and over-processing. The Kaizen Institute emphasizes that sales teams should eliminate waste to focus 

on value-added activities, enhancing productivity and customer service.  

Operational Efficiency 

Operational efficiency is a critical concept for organizations across all sectors, focusing on maximizing 

output with minimal input. It involves streamlining processes, reducing waste, and optimizing resource 

utilization to achieve the best possible performance. In an increasingly competitive global landscape, 

enhancing operational efficiency is essential for achieving sustainable growth and maintaining a 

competitive advantage. Operational efficiency is often defined as the ratio between an organization's 

inputs and outputs. Inputs typically include resources such as time, labour, capital, and materials, while 

outputs encompass products, services, revenue, and customer satisfaction. The goal is to improve this 

ratio, either by reducing the inputs required for a given level of output or by increasing the output 

achieved with the same level of input. Operational efficiency is the organization's ability to decrease 

wastage of inputs and maximize resource utilization.  

2.2 Theoretical Framework 

John Elkington first proposed the idea of the Triple Bottom Line (TBL), sometimes referred to as the 

"three pillars" or "three Ps" of sustainability, in 1994. He founded the consulting firm Sustain Ability 

and is a British management consultant. According to the principle, businesses should prioritize three 

things: profit, people, and the environment. This entails taking into account a company's social and 

environmental effects in addition to its financial performance when assessing its success. Businesses 

used to function exclusively to support their bottom line. The triple bottom line (TBL) was first 

proposed in 1994 by author and businessman John Elkington in an effort to change the financial 

accounting-focused corporate system into a complete strategy that gauges success and effect. Some 

companies started to understand the link between social well-being, environmental health, and an 

organization's resilience and financial success as a result of the triple bottom line theory and its 

implementation. Organizations must completely account for all costs related to conducting business in 

order to obtain a comprehensive view of their operations that goes beyond what is shown in their profit 

and loss statements. 

i. It is a transformation framework designed to assist companies and organizations in their 

transition to a more sustainable and regenerative future.  

ii. TBL provides instruments to assist a company in measuring, comparing, establishing objectives, 

and ultimately moving toward more sustainable models and systems. 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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76 | P a g e  

iii. It shows that a company cannot account for all of the costs associated with conducting business 

and will not prosper in the long run if it is solely concerned with making money while neglecting people 

and the environment.  

By incorporating an organization's contributions to social well-being, environmental health, and a just 

economy, the triple bottom line hypothesis broadens the scope of traditional commercial success 

indicators. The three "P's"—people, planet, and prosperity—are frequently used to describe these 

bottom line categories. The triple bottom line is composed of three categories, however it's crucial to 

keep in mind that they are not distinct from one another. The three "P's" are all related when viewed 

through the perspective of systems theory. Since systems thinking is the cornerstone of sustainability, 

any endeavor that pertains to people, the planet, or prosperity will also have an effect on the others. 

 
The triple bottom line, often referred to as the three “P’s”: people, planet, and prosperity. 

People  

Employees, the communities in which a business operates, people in the supply chain, future 

generations, and consumers are just a few of the stakeholders that people take into account (as opposed 

to merely shareholders). This part of the triple bottom line revolves around the relationship with 

corporate social responsibility (CSR). CSR is the duty of stakeholders to hold organizations accountable 

for their activities and the duty of organizations to satisfy the requirements of their stakeholders. 

Human rights advancement, poverty and hunger alleviation, diversity, equity, and inclusion, gender 

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ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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equity, maintaining a safe and healthy workplace, community involvement, and volunteerism are a few 

activities that a firm may think about include in its CSR objectives. Stakeholders benefit from CSR 

activities, but businesses also profit when they include CSR into their business plan. Businesses 

frequently share best practices with other companies and organizations as part of their dedication to 

advancing CSR initiatives. 

Planet 

Planet takes into account how a company or organization interacts with the environment and its 

ecological systems. Stakeholders may now hold companies more accountable for their activities because 

to a variety of factors, including public opinion, consumer purchasing power, the speed and 

transparency of information sharing on social media, and even industry-led activism (like Patagonia's 

1 percent for the Planet campaign). This is demonstrated by stakeholders praising an organization for 

its beneficial effects and criticizing its negative ones. It is likely to have an effect on who customers 

choose to support and who they purchase from when that opinion becomes widely known. 

In addition to the potential effects that corporate operations may have on the environment, society, and 

economy, stakeholders are becoming more conscious of the significance of global concerns like social 

justice and climate change. Actually, according to a 2020 Climate Change in the American Mind survey, 

"nearly six out of ten Americans, or roughly 58 percent, are now either 'Alarmed' or 'Concerned' about 

global warming." The percentage of people who were "alarmed" almost tripled between 2014 and 

2019.Businesses have been implementing more environmentally friendly strategies over the last few 

decades. Large corporations such as AT&T, DELL, EASTON, Hewlett Packard, Kohler Co., Levi Strauss 

& Co., and Target, to mention a few, have advanced down the sustainability road in recent years by 

having a net-positive or regenerative effect on society and the environment. 

Prosperity 

Prosperity takes into account the economic metrics that a company or organization can control, such 

as providing livable salaries, using ethical suppliers, and ensuring worker health and safety. The triple 

bottom line theory's perspective on people, the environment, and prosperity makes it systemic. The 

Sustainable Development Goals (SDGs) were established by the United Nations (UN) to "ensure all 

human beings can enjoy prosperous and fulfilling lives and that economic, social, and technological 

progress occurs in harmony with nature" in light of this interconnectedness. Numerous UN SDGs seek 

to enhance a variety of aspects pertaining to people, the environment, and economic prospects. 

Providing decent work (safe working conditions, living pay, and compassionate leadership) and 

economic growth for people in particular areas is one of the many prosperity-focused agendas. 

2.3 Empirical Review 

Njoku (2021) conducted a study on Leadership and Continuous Improvement in the Nigerian 

Leadership and Continuous Improvement in the Nigerian. There is a high failure rate of continuous 

improvement (CI) initiatives in the beverage industry. Continuous improvement initiatives could help 

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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78 | P a g e  

beverage manufacturing managers improve product quality, efficiency, and overall performance. 

Grounded in the transformational leadership theory, the purpose of this quantitative co relational study 

was to examine the relationship between idealized influence, intellectual stimulation, and CI. Nigerian 

beverage industry managers (N = 160) who participated in the study completed the Multifactor 

Leadership Questionnaire Form 5X-Short, and the Plan, Do, Check, and Act (PDCA) cycle. The results 

of the multiple linear regression were statistically significant, F(2, 157) = 16.428, p < 0.001, R2 = 0.173. 

Idealized influence (ß = 0.242, p = 0.000) and intellectual stimulation (ß = 0.278, p = 0.000) were both 

significant predictors. The implications for positive social change include the potential to increase the 

opportunity for the growth and sustainability of the beverage industry 

Ogbuke, Eneh, and Okwor (2023) conducted a study on Employee Performance Management and 

Performance of Food Beverage Manufacturing Firms of Enugu State The study evaluated the employee 

performance management practices and performance of food beverage manufacturing firms of Enugu 

State. The specific objectives were to: examine the relationship between engaged employees and the 

profitability and evaluate the relationship between identification of talent and output of food 

manufacturing firms of Enugu State. The area of the study was the SMEs in Enugu State. The study 

used the descriptive survey design approach. The primary source of data was the administration of 

questionnaire. A total population of 911 selected staff of the study organisations. The hypotheses were 

analysed using Pearson correlation coefficient (r). The findings indicated there was significant positive 

relationship between Engaged employees and the profitability r (95, n=228), = .453 < .985, P <. 05 and 

there was significant positive relationship between identification of talent and output of food 

manufacturing firms of Enugu State r (95, n=228), = .416 < .971, P <. 05. The study concluded that 

engaged employees and talent had significant positive relationship with the profitability and output of 

food beverage manufacturing firms of Enugu State.  

Onoh, Chinasa, and Hubs, (2022) conducted a study on Development on the Waste Reduction of Food, 

Beverage and Tobacco Manufacturing Firms in Enugu State. The study evaluated the sustainability 

development on the waste reduction of food, beverage and tobacco manufacturing. The specific 

objectives were to: examine the effect of employee equal opportunity on the prevention of waste and 

evaluate the effect of maintenance skills on the standard costing of Food, Beverage and Tobacco 

Manufacturing firms in Enugu state. The study employed survey method research. Data was presented 

and analysed by mean score (3.0 and above agreed while below 3.0 disagreed) and Z-test was used to 

test the hypotheses. The findings indicated that Employee equal opportunity had positive effect on the 

prevention of waste, (7.530 < 8.532, p = < .05) and Maintenance of skills had positive effect on the 

standard costing of Food, Beverage and Tobacco Manufacturing firms in Enugu state, (4.965 < 6.654, 

p = < .05).The study concluded that Employee equal opportunity and Maintenance of skills had positive 

effect on the prevention of waste, standard costing and reusable products of Food, Beverage and 

Tobacco Manufacturing firms in Enugu state.  

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American Research Journal of Economics, Finance and Management  
Volume 13 Issue 3, July-September 2025 

ISSN: 2836-9416 

Impact Factor: 6.41 

Journal Homepage: https://americaserial.com/Journals/index.php/ARJEFM 

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Rolker, Eisler, Cardenas, Deeney, and Takahashi (2022) conducted a study on Food waste interventions 

in low-and-middle-income countries: A systematic literature. Reduction of food waste in low-and-

middle-income countries (LMICs) can provide multi-layered benefits for their sustainable 

development, through improved food security, enhanced income as well as the creation of 

environmentally friendly secondary markets. Food systems, however, are often characterised by a 

complex network of actors across the value chain, where a parochial intervention at a local scale does 

not always achieve a globally optimal outcome. Here, we systematically reviewed 8318 studies for the 

current evidence associated with the impact of interventions pursuing food waste reduction in LMICs. 

We first classified interventions by the target stage within the value chain and by the mechanism of 

action, and then further based on whether they are primarily designed to prevent or mitigate (recycle, 

reuse, remanufacture, repurpose and recover) the wastage of the commodity. We found a near-

complete disconnect between preventive and mitigative interventions amongst the studies, with the 

former only investigated at production, storage and transportation stages and the latter only at 

wholesale and consumption stages. No identified study employed preventive and mitigative measures 

together to explore the combined level of efficacy. We also identified a strong bias in favour of material-

based interventions, with little attention given to knowledge-based alternatives or local capacity 

building. 

3. Methodology 

A survey research design was selected for the investigation. A standardized questionnaire with a point 

Likert scale was used to collect data for the study. The study's population consists of workers from the 

selected food producing enterprises in South-East Nigeria. The workforce was made up of both senior 

and junior employees from various divisions of food and beverage production enterprises. In this study, 

3,565 employees were included in the sample. The sample size for the study consisted of 347 

respondents. The sample size was calculated using Freund and William's statistical technique. The data 

was analyzed using the mean, standard deviation, and fundamental percentages. (SPSS version 20, a 

program for descriptive statistics).  

4 Data Presentation and Analyses 

4.1 Distribution and returned Questionnaire 

The presentation and interpretation of data were based on the questionnaire administrated to the staff 

of the Southeast Nigeria's food industry.  

Table 4.1 Distribution and Return of the Questionnaire  

Firms Distributed   No 

Returned  

percent No not 

Returned  

Percent 

1. Nigeria Breweries, Aba 50 49 14 2 1 

2.M.O. Nnaji Bakeries, Aba 17 16 5 1 - 

3.Tummy Tummy foods, Nnewi 37 35 10 2 1 

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ISSN: 2836-9416 

Impact Factor: 6.41 

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4.Nigeria Bottling Co. Ltd., Onitsha 44 42 12 2 1 

5.Jaypee Enterprises, Uburu 24 23 7 1 - 

6 Abakaliki Rice Cluster 46 42 12 4 1 

7.Nigerian Breweries Plc, Enugu 37 35 10 2 1 

8.Aqua Ralpha Investment, 9th Mile 42 36 10 6 2 

9.Emmerald food, Owerri 38 37 11 1 - 

10.Jacob Wine, Orlu 12 11 3 1 - 

Total 347 326      93.0 21 7.0 

Source: Field Survey, 2024 

Table 4.1 shows that of the 347 distributed copies of the questionnaire, three hundred and twenty-six 

(326) were returned representing ninety-one (91) percent and used, while twenty-one (21) copies of the 

questionnaire representing seven (7) percent were not returned and were not used. This shows a high 

respondents’ rate. 

4.2 Bio Data 

The bio-data shows the gender distribution, marital status of respondents, educational qualifications, 

and years of experience and age of the respondents under study. 

Table 4.2.1 Gender Distribution 

 Frequency Percent Valid 

Percent 

Cumulative 

Percent 

Male 183 56.1 56.1 56.1 

Female 143 43.9 43.9 100.0 

Total 326 100.0 100.0  

Source: Field Survey, 2024 

 From table 4.2.1 it was observed that 183 respondents out of 326 representing 56.1 percent were males 

whereas 143 respondents representing 43.9 percent were females. This indicated that male were more 

than the females. 

 

 

 

Table 4.2.2 marital status of Respondents 

 Frequency Percent Valid 

Percent 

Cumulative 

Percent 

Single 109 33.4 33.4 33.4 

Married 191 58.6 58.6 92.0 

Widowed 20 6.1 6.1 98.1 

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ISSN: 2836-9416 

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Divorced 6 1.9 1.9 100.0 

Total 326 100.0 100.0  

Source: Field Survey, 2024 

Table 4.2.2 reveals that 109 respondents out of 326 representing 33.4 percent were single, 191 

respondents representing 58.6 percent were married. 20 respondents representing 6.1 percent were 

widowed. 6 respondents representing 1.9 percent were divorced.  

Table 4.2.3 Educational qualifications of the Respondents 

 Frequency Percent Valid 

Percent 

Cumulative 

Percent 

WASC/GCE 88 27.0 27.0 27.0 

OND/NCE 88 27.0 27.0 54.0 

HND/B.Sc. 92 28.3 28.3 82.3 

MBA/M.Sc. 37 11.3 11.3 93.6 

PhD 21 6.4 6.4 100.0 

Total 326 100.0 100.0  

Source: Field Survey, 2024 

Table 4.2.3, reveals that 88 respondents out of 326 representing 27.0 percent were holders of 

WASC/GCE, 88 respondents representing 27.0 percent were holders of NCE/OND, 92 respondents 

representing 283 percent were holders of HND and BSC, 37 respondents representing 11.3 percent were 

holders of Masters degree and 21 respondents representing 6.4 percent were holders of PhD. 

Table 4.2.4:   Years of Experience 

 Frequency Percent Valid 

Percent 

Cumulative 

Percent 

less than 1 - 

2years 
82 25.2 25.2 25.2 

3-5years 208 63.8 63.8 89.0 

6-10years 30 9.2 9.2 98.2 

11 years and 

above 
6 1.8 1.8 100.0 

Total 326 100.0 100.0  

Source: Field Survey, 2024 

Table 4.2.4, 82 respondents out of 326 representing 25.2 percent have less than 1 – 2 years experience, 

208 respondents with 63.8 percent were within the years experience of 3 – 5 years, 30 respondents 

representing 9.2 percent were within the years’ experience 6-10years, 6 respondents representing 1.8 

percent were within the 11 years and above. 

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Table 4.2.5 Age of the respondents 

 Frequenc

y 

Percen

t 

Valid 

Percent 

Cumulativ

e Percent 

25-30years 53 16.3 16.3 16.3 

31-35years 77 23.6 23.6 39.9 

36-40years 89 27.3 27.3 67.2 

45- 50years 19 5.8 5.8 73.0 

51years and above 88 27.0 27.0 100.0 

Total 326 100.0 100.0  

Source: Field Survey, 2024 

Table 4.2.5, 53 respondents out of 326 representing 16.2 percent were within the age of 25 - 30years, 

77 respondents with 23.6 percent were within the age bracket of 31-35, 89 respondents representing 

27.3 percent were within the age bracket of 36 – 40years, 19 respondents representing 5.8 percent were 

within the age bracket of 45-50 years while 88 respondents representing   27.0 percent were within the 

age bracket of 51 years and above. This implies that greater proportion of the respondents fall within 

the ages of 36 - 40 years. 

4.3   Data Presentation and Analyses 

i. 4.3.1 The effect of continuous improvement process on operational efficiency in 

Southeast Nigeria's food industry. 

iii. Table 4.3.1.1: Responses on the effect of continuous improvement process on 

operational efficiency in Southeast Nigeria's food industry. 

  5 

SA 

4 

A 

3 

N 

2 

D

A 

1 

SD 

∑FX - 

X 

SD Decisi

on 

1 There is improvement 

to service which 

promotes best 

outcomes 

900 

180 

 

55.2 

  140 

35 

10.7 

129 

43 

13.2 

84 

42 

12.

9 

26 

26 

8.0 

1,279 

326 

 

100.

0 

3.92 1.385 Agree 

2 Continuous 

improvement enables 

the organisations to 

make an ongoing 

915 

183 

56.1 

112 

28 

8.6 

117 

39 

12.0 

86 

43 

13.

2 

33 

33 

10.1 

1263 

326 

3.87 1.453 Agree 

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commitment to change 

and apply better success 

 

100.

0 

3 The continuous, 

interactive 

improvement is linked 

with innovation which 

helps customers in 

getting better services.    

640 

128 

39.3 

112 

28 

8.6 

279 

93 

28.5 

66 

33 

10.

1 

44 

44 

13.5 

1141 

326 

100.

0 

3.5 1.433 Agree 

4 Small incremental 

changes add up to 

significant results that 

prevent damaged 

goods.  

725 

145 

44.5 

 324 

  81 

 

24.8 

   93 

  31  

9.5   

26 

13 

4.

0 

56 

56 

17.2 

1224 

326 

100.

0 

 

3.75 1.481 Agree 

5 Continuously reviewing 

results and adopting 

new measures 

ameliorate spoilt goods    

975 

195 

59.8 

188 

47 

14.4  

  60 

  20 

  6.1 

76 

38 

11.

7 

26 

26 

8.0 

1325 

326 

100.

0 

4.06 1.358 Agree 

 Total Grand mean 

and standard 

deviation 

      19.1 7.11  

Source: Field Survey, 2024 

Table 4.3.1.1., 215 respondents out of 326 representing 65.9 percent agreed that there is improvement 

to service which promotes best outcomes with mean score 3.92 and standard deviation of 1.385. 211 

responden4ts representing 64.7 percent agreed that continuous improvement enables the 

organisations to make an ongoing commitment to change and apply better success with mean score of 

3.87 and standard deviation of 1.453.  156 respondents representing 47.9 percent agreed that the 

continuous, interactive improvement is linked with innovation which helps customers in getting better 

services with mean score of 3.5 and standard deviation of 1.433.  226 respondents representing 69.3 

percent agreed with that Small incremental change add up to significant results that prevent damaged 

goods Mean score of 3.75 and 1.481. 242 respondents representing 74.2 percent agreed that 

continuously reviewing results and adopting new measures ameliorate spoilt goods with a mean score 

of 4.06 and standard deviation 1.358. 

Table 4.3.4.1 The effect of eliminating waste on operational efficiency in Southeast 

Nigeria's food industry. 

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Table 4.3.4.1: Responses on the effect of eliminating waste on operational efficiency in 

Southeast Nigeria's food industry. 

  5 

SA 

4 

A 

3 

N 

2 

D

A 

1 

SD 

∑FX - 

X 

SD Decisi

on 

1 The food and beverage 

firms reduce excess 

inventory to increase 

the profitability. 

555 

111 

 

34.0 

  

396 

99 

30.4 

45 

15 

4.6 

20

4 

68 

20

.9 

33 

33 

10.1 

1233 

326 

 

100.

0 

3.78 1.399 Agree 

2 The organization 

converts raw materials 

into service to help 

increase cash flow 

715 

143 

43.9 

 

540 

135 

41.4 

 

48 

 16 

4.9 

 

 6 

3 

 .9 

 

29 

29  

8.9 

 

1338 

326 

 

100.

0 

4.10 1.148 Agree 

3 Adopting just- in – time 

services reduce 

expenses of the 

organization 

960 

192 

59.8 

376 

94 

28.8 

45 

15 

4.6 

36 

18 

5.5 

7 

7 

2.1 

1424 

326 

100.

0 

4.37 .957 Agree 

4 Investing in efficiency 

improvements in the 

organisation attracts 

cash flow. 

835 

167 

51.2 

 464 

  116 

 

35.6 

   39 

   13 

4.0   

36 

18 

5.5 

12 

12 

3.7 

1386 

326 

100.

0 

 

4.25 1.022 Agree 

5 Ordering exactly the 

right number of 

products drives income. 

425 

85 

26.1 

648 

162 

49.7  

  39 

  13 

  4.0 

10

6 

53 

16.

3 

13 

13 

4.0 

1231 

326 

100.

0 

5.22 1.124 Agree 

 Total Grand mean 

and standard 

deviation 

      21.7

2 

5.65  

Source: Field Survey, 2024 

Table 4.3.4.1., 210 respondents out of 326 representing 64.4 percent agreed that the food firms reduces 

excess inventory to increase the operational efficiency with mean score 3.78 and standard deviation of 

1.399.  278 respondents representing 85.3 percent agreed that the organization converts raw materials 

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into service to help increase cash flow with mean score of 4.10 and standard deviation of 1.148. 286 

respondents representing 88.6 percent agreed that adopting just- in – time services reduce expenses of 

the organization with mean score of 4.37 and standard deviation of .957.  283 respondents representing 

86.8 percent agreed that investing in efficiency improvements in the organisation attracts cash flow 

with mean score of 4.25 and standard deviation of 1.022. 247 respondents representing 75.8 percent 

agreed that ordering exactly the right number of products drives income with a mean score of 5.22 and 

standard deviation 1.124. 

4.4 Test of Hypotheses 

4.4.1 Hypothesis One: Continuous improvement process has significant effect on the 

operational efficiency in Southeast Nigeria's food industry. 

One-Sample Kolmogorov-Smirnov Test 

 There is 

improveme

nt to 

service 

which 

promotes 

better 

outcomes. 

Continuous 

improvement 

enables the 

organisations 

to make an 

ongoing 

commitment to 

change and 

apply better 

success. 

The 

continuous, 

interactive 

improvement 

is linked with 

innovation 

which helps 

customers in 

getting better 

services. 

Small 

incremental 

changes add 

up to 

significant 

results that 

prevent 

damaged 

goods 

Continuous

ly 

reviewing 

results and 

adopting 

new 

measures 

ameliorate 

spoilt 

goods 

N 326 326 326 326 326 

Uniform 

Parameters
a,b 

Minimu

m 
1 1 1 1 1 

Maximu

m 
5 5 5 5 5 

Most 

Extreme 

Differences 

Absolute .552 .561 .393 .445 .598 

Positive .080 .101 .135 .172 .080 

Negative -.552 -.561 -.393 -.445 -.598 

Kolmogorov-

Smirnov Z 
9.969 10.135 7.089 8.031 10.800 

Asymp. Sig. (2-

tailed) 
.000 .000 .000 .000 .000 

a. Test distribution is Uniform. 

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b. Calculated from data. 

Decision Rule 

If the calculated Z-value is greater than the critical Z-value (i.e. Zcal > Zcritical), reject the null 

hypothesis and accept the alternative hypothesis accordingly. 

Result 

With Kolmogorov-Smirnon Z – value of 7.098 < 10.089 and on Asymp. Significance of 0.000, the 

responses from the respondents as display in the table is normally distributed. This affirms the 

assertion of the most of the respondents that continuous improvement process had significant positive 

effect on the operational efficiency in Southeast Nigeria's food industry. 

Decision  

Furthermore, comparing the calculated Z- value of 7.098 < 10.089 against the critical Z- value of .000 

(2-tailed test at 97percent level of confidence) the null hypothesis was rejected. Thus, the alternative 

hypothesis was accepted which states that continuous improvement process had significant positive 

effect on the operational efficiency in Southeast Nigeria's food industry. 

4.4.2 Hypothesis two: Eliminating waste has significant effect on operational efficiency 

in Southeast Nigeria's food industry. 

One-Sample Kolmogorov-Smirnov Test 

 The food and 

beverage 

firms reduce 

excess 

inventory to 

increase the 

profitability 

The 

organizatio

n converts 

raw 

materials 

into service 

to help 

increase 

cash flow. 

Adopting 

just- in – 

time 

services 

reduce 

expenses of 

the 

organizatio

n 

Investing in 

efficiency 

improveme

nts in the 

organisatio

n attracts 

cash flow. 

Ordering 

exactly the 

right 

number of 

products 

drives 

income. 

N 326 326 326 326 326 

Uniform 

Parametersa,b 

Minimum 1 1 1 1 1 

Maximum 5 5 5 5 5 

Most Extreme 

Differences 

Absolute .394 .603 .627 .618 .508 

Positive .101 .089 .021 .037 .040 

Negative -.394 -.603 -.627 -.618 -.508 

Kolmogorov-Smirnov Z 7.117 10.883 11.326 11.160 9.166 

Asymp. Sig. (2-tailed) .000 .000 .000 .000 .000 

a. Test distribution is Uniform. 

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b. Calculated from data. 

Decision Rule 

If the calculated Z-value is greater than the critical Z-value (i.e. Zcal > Zcritical), reject the null hypothesis 

and accept the alternative hypothesis accordingly. 

Result 

With Kolmogorov-Smirnon Z – value of 7.117 < 11.160 and on Asymp. Significance of 0.000, the 

responses from the respondents as display in the table is normally distributed. This affirms the 

assertion of the most of the respondents that eliminating waste had significant positive effect on 

operational efficiency in Southeast Nigeria's food industry. 

Decision  

Furthermore, comparing the calculated Z- value of 7.117 < 11.160 against the critical Z- value of .000 

(2-tailed test at 97percent level of confidence) the null hypothesis was rejected. Thus, the alternative 

hypothesis was accepted which states that eliminating waste had significant positive effect on 

operational efficiency in Southeast Nigeria's food industry. 

From the result of the hypothesis one, the calculated Z- value of 7.098 < 10.089 against the critical Z- 

value of .000 which implies that Continuous improvement process had significant positive effect on the 

operational efficiency in Southeast Nigeria's food industry. 

The hypothesis two, the calculated Z- value of 7.117 < 11.160 against the critical Z- value of .000 which 

implies that eliminating waste had significant positive effect on operational efficiency in Southeast 

Nigeria's food industry. 

5 Conclusion 

In conclusion, the application of Sustainable Lean Six Sigma in Southeast Nigeria's food industry has 

demonstrated a significant positive effect on operational efficiency. The continuous improvement 

process has led to enhanced performance by fostering a culture of ongoing refinement and adaptation. 

Additionally, the focus on eliminating waste has resulted in more streamlined operations, reducing 

costs and increasing productivity. These findings indicate that the integration of Sustainable Lean Six 

Sigma principles can effectively address the unique challenges faced in this sector, ultimately driving 

improvements in efficiency and competitiveness. Moving forward, stakeholders should continue to 

leverage these methodologies to sustain growth and enhance operational capabilities within the 

industry. 

Recommendation 

To maximize the benefits of Sustainable Lean Six Sigma in Southeast Nigeria's food industry, the 

following recommendations are proposed: 

i. Organizations should invest in comprehensive training for employees at all levels to deepen their 

understanding of continuous improvement processes. This will empower staff to identify inefficiencies 

and contribute to ongoing enhancement efforts. 

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ii. Companies should adopt specific strategies focused on waste elimination, such as value stream 

mapping and root cause analysis. Regular assessments should be conducted to identify areas for 

improvement and track progress. 

 

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