64 © 2020 Adama Science & Technology University. All rights reserved Ethiopian Journal of Science and Sustainable Development e-ISSN 2663-3205 Volume 7 (2), 2020 Journal Home Page: www.ejssd.astu.edu.et ASTU Research Paper Comparative Analysis of Inflation Dynamics of Three African Countries: Ethiopia, Kenya and South Africa Desa Daba Fufa  Department of Statistics, College of Computing and Informatics, Haramaya University, P.O. Box138, Dire Dawa, Ethiopia Article Info Abstract Article History: Received 3 February 2020 Received in revised form 22 April 2020 Accepted 17 Jun 2020 This paper examines a comparative view of the inflation dynamics in three African countries. The study used monthly data from January 2007 to April 2018. To achieve the objectives, the study was deployed varieties of econometric methods. The exploratory analysis reveals that inflation of the sampled countries exhibits similar trends over the long run. The Johansson Co-integration test result evince that inflation, oil price and exchange rate of Ethiopia and South Africa had a long run relationship. Exchange rates had significant positive effects on inflation dynamics of both countries while world oil price contributes positively in Ethiopia but negatively in South Africa. In the short run, inflation in Kenya was found to be a sign of Ethiopia’s inflation. Likewise, in South African inflation was an indicator of the inflation in Kenya whereas inflation in Kenya and Ethiopia could not predict inflation would occur in South Africa. Furthermore, the outcome of the impulse response function demonstrates that exchange rates and oil price shocks affected inflation dynamics of the sampled countries at different stages both directly and indirectly. In the short run, shocks to inflation have an interaction effect across the selected countries. The findings also report that world oil prices are not equally contributes for inflation dynamics in the sampled countries. Keywords: Co-integration Granger causality Inflation dynamics Impulse response function Interaction effect 1. Introduction Inflation refers to the continuous upsurge in the aggregate level of prices of goods and services in an economy (Romer, 2012). It is clearly known that different economies in different parts of the world experience inflation. The severity level may differ from one country to another due to a number of historical country-specific causes. Majority of developing countries experienced elevated inflation. Even if Ethiopia has had a historically low inflation rate compared to other developing countries, in recent time it is experiencing a high inflation rate. High inflation is often linked with lesser growth and financial crises. As Al-Shammari and Al-Sabaey (2012) stated, emerging  Corresponding author, e-mail: dabadesa6@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.197 countries are disposed to currency and financial crises more than the industrialized countries. The surge of price is further associated with non-proportional production and consumption of goods and services. This can be due to insufficient investments and steady population growth. High inflation can be a serious problem for many economies worldwide. Currently, majority of the African countries like Ethiopia, South Sudan, Zimbabwe, Kenya, etc. experienced elevated inflation (Durevall and Sjö, 2012; Gudina et al., 2018; Okara and Mutuku , 2019). Knowing the causes of soaring inflation and it’s the dynamic nature of inflation has always been http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 65 a key concern of academics and monitory policymakers around the world. A large body of literature has documented the challenges posed by spiraling inflation on the countries’ economy and factors that contribute to rising inflation dynamics (Chou and Tseng, 2011; Durevall et al., 2012; Misati et al., 2013; Abounoori et al., 2014; Brahmasrene et al., 2014; Kargi, 2014; Christine et al., 2015; Habtamu, 2015; Kavila, and Le Roux, 2016; Anh, et al., 2017). These researchers have identified some driving forces of inflation: world food prices, world energy prices such as oil price, domestic food prices, excess money supply, exchange rates, and domestic agricultural supply shocks. Durevall and Sjö (2012) found that inflation dynamics in Ethiopia and Kenya were driven by similar factors; of which world food prices and exchange rates had a long-run impact, whereas money growth and agricultural supply shocks had short-to-medium run effects. Even though numerous researches have been done, there has been no agreement on the sources of high inflation experienced in recent years and no study scrutinized the interaction effects of inflation dynamics across the countries which are the focus of this study. Inflation dynamics across countries may move together due to some common shocks (for instance world oil price shock, demand and supply shocks) and they may have interaction effects on each other if countries have integrated market system, economic and geographical ties (Eickmeier and Kühnlenz, 2018). Economic and trade integration in Africa is not a recent phenomenon. Particularly, many of the economic and trade integration agreements between Ethiopia and Kenya were signed at various times, and they have warm trade relations. For example, the 2017 import and export data from the Ethiopian Revenues and Customs Authority shows that, Ethiopia exported $ 67,717 to Kenya and $ 10,532 to South Africa. It also imported $ 35,685 and $ 203,974 from Kenya and South Africa respectively. Ethiopia is the only country that shares borders with all the other countries in the Horn of Africa and is the headquarters of the African Union. Since the selected countries have strong economic and commercial ties, this research examined the inflation dynamics and interaction effects among Ethiopia, Kenya and South Africa. The study tried to address the following research questions and extends the literatures by considering the research questions: a) To what extent the impacts of the world oil price shock on inflation differ across the selected countries?; b) What are the drivers of domestic inflation dynamics?; and c) Is there any factual interaction effects of inflation dynamics across the selected countries? The research was carried out to investigate the trend of inflation, illustrate the granger causal relationship of inflation dynamics and identify the major driving force(s) of high inflation dynamics in three African countries. Finally, it suggested the best strategies to manage the variability of inflation for the policy makers and other stakeholders. 2. Methods Ethiopia, Kenya and South Africa were purposively selected as the focus of this research, for they strong trade integration and economic ties. Kenya and South Africa are top trading partners of Ethiopia. Thus, the researcher considered Ethiopia’s, Kenya’s and South Africa’s inflation dynamics for analysis. For this study, monthly time series data spanning the period from January 2007 to April 2018 concerning Ethiopian consumer price index (ETHCPI), Kenyan consumer price index (KCPI) and South African consumer price index (SCPI), exchange rates ((Ethiopian Birr/USD Exchange rate (ETHEXR), Kenyan Shilling/ USD exchange rate (KEXR) and South African Rand/USD exchange rate (SEXRT)) and world oil price were collected from National Bank of Ethiopia and International Monitory Fund. Various parameters such as Consumer Price Index (CPI), Wholesale Price Index (WPI) and Sensitive Price Indicator (SPI) were used for measuring inflation. Consumer Price Indexes (CPI) were used as a proxy for inflation. Consumer prices are very much linked with the world oil prices because oil products are not only used as a final product but are also used as an input in many of the production processes and economic activities. From 2000 to 2008, world oil prices created new records that severely affected the economy of every country of the world (Asghar and Naveed, 2015). The study used both descriptive and inferential statistics for data analysis. Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 66 2.1. Econometric Model Specification and Tests 2.1.1. Tests of stationarity In econometric analysis involving time series data, before any kind of econometric estimation takes place, the collected data should be tested for their stationarity. For this purpose, the Augmented Dickey-Fuller (ADF) test and Phillip-Perron (PP) tests were used to tests for the stationarity. The ADF test avoids the problem of Dickey-Fuller because it corrects for serial correlation; by adding lagged difference terms (Gujariti, 2004). The ADF test can be represented as: ∆𝑌𝑡 = 𝛾1 + 𝛾2𝑡 + 𝛿𝑌𝑡−1 + ∑ 𝛼𝑖 𝑝 𝑖=1 ∆𝑌𝑡−𝑖 + 𝑡 (1) where, 𝛾1, 𝛾2, 𝛿, and 𝛼 are the coefficients, t is the stochastic trend, 𝑡 is a white noise error term and ∆𝑌𝑡−1=𝑌𝑡−1-𝑌𝑡−2, ∆𝑌𝑡−2=𝑌𝑡−2-𝑌𝑡−3, etc. The test statistic is given below: )ˆ( ˆ   SE Z t  where, )ˆ(SE standard error of ̂ . Hypothesis tests: 0: Ho where, 1  . To perform the tests, conventional F-test is used but compares the test statistic with the critical F-values developed by Dickey and Fuller. The Phillips-Perron test is an alternative method for unit root tests. A PP test ignores any serial correlation in the error term without adding lagged difference terms and they use the standard DF or ADF test but adjust the t-ratio so that the serial correlation does not affect the asymptotic distribution of the test statistic. 2.1.2. Co-integration tests Many macroeconomic variables are not stationary at a level but a linear combination of two or more non- stationary series may be stationary and these series are said to be co-integrated. If integrated of order one variables are co-integrated, they are moving together so that there is some long run relationship between them. Traditional time-series models have failed to fully capture the behavior of such complex relationship: The Johansen's approach takes its initial point in the vector auto regression (VAR) order p specified by: o 1 1 2 2 ... (2) t t t p t p t Y Y Y Y           The above VAR (p) can be re-specified as: tt p t itt YYY        1 1 1 1o where,    p ij ji p t i andI 11 If the coefficient matrix  has reduced rank r 0, t = 1,..., T (8) t t t p t p t Y Y Y Y              where, Yt is a vector of length k, o  is a k-dimensional vector, Φ is a k × k matrix of autoregressive coefficients for j = 1, 2, ……, p. , and { t  } is a sequence of serially uncorrelated random vectors with mean zero and covariance matrix Σ. Yt is a vector of length k. There are k equations. The coefficient matrix Φ measures the dynamic dependence of Yt and are unknown and to be estimated from the observed data. 2.1.5. Vector Error Correction Model (VECM) The use of Vector Autoregressive Models (VAR) and Vector Error Correction Models (VECM) for analyzing dynamic relationships among financial variables has become common in the literature. From the above VAR (p) model specification, we can rewrite as a VECM. ∆y t =ϑ+ Π𝑦𝑡−1+ ∑ Γ𝑖 𝑝−1 𝑖=1 ∆𝒚𝑡−𝑖 + 𝜺𝑡 (9) where, Π𝑖 = αβ′,Γ𝑖 = − ∑  𝑗 𝑝 𝑗=𝑖+1 and 𝐼𝑛is an identity matrix. Π and the short-run parameter Γ𝑖 i=1, 2,…, p-1 are p × p matrices of coefficients. The VECM expressed above is convenient because the hypothesis of cointegration can be stated in terms of the long-run impact matrix, Π. 2.1.7. Granger Analysis This study uses Engle-Granger causality test to analyze the relationship between the selected variables. Let Xt and Yt be two stationary (after possible transformations) time series of length T. A variable Xt is said to Granger causes another variable Yt, if Yt can be better predicted from the past of Xt and Yt together than the past of Yt alone, other relevant information being used in the prediction (Pierce, 1977). Likewise the researcher was interested to see the grander causality of inflation dynamics between the selected countries and other selected variables. 2.1.8. Impulse Response Function The VAR model can be used for structural inference and policy analysis. In structural analysis, certain assumptions about the causal structure of the data under investigation are imposed, and the resulting causal impacts of unexpected shocks or innovations to specified variables on the variables in the model are summarized. Granger-causality may not tell us the complete story about the interactions between the variables of a system. In applied work, it is often of interest to know the response of one variable to an impulse in another variable in a system that involves a number of further variables as well. These causal impacts are usually summarized with impulse response functions and forecast error variance decompositions. Identification of the underlying structural shocks is necessary if we are to estimate the effects of an exogenous shock to a single variable on the dynamic paths of all of the variables of the system, which we call impulse-response functions (IRFs). The impulse response function can be plotted as the period multipliers against the lag length. An impulse response function traces the response of a variable of interest to an exogenous shock. Often the response is portrayed graphically, with horizon on the horizontal axis and response on the vertical axis. It traces the effect of a one standard deviation shock to one of the innovations on current and future values of the endogenous variables. A shock to the i th variable directly affects the j th variable, Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 68 and may also transmit to all of the endogenous variables through the dynamic structure of the VAR. Any covariance stationary VAR (p) process has a Wald representation of the form: The impulse response function (IRF) of a dynamic system is its output when presented with a brief input signal, called an impulse. More generally, an impulse response refers to the reaction of any dynamic system in response to some external change. A VAR was written in vector MA (∞) form as: 1 1 2 2 ... (10) t t t t Y              Thus, the matrix s  has the interpretation s t st Y       ' that is, the row i, column j element of s  identifies the consequences of one unit increase in the j th variable’s innovation at date t ( jt ) for the value of the i th variable at time t+s( sit Y  ), holding all other innovations at all dates constant. ti sti Y '   as a function of s is called the impulse response function. It describes the response of sit Y  a one-time impulse in tj Y with all other variables dated t or earlier held constant. 3. Results and Discussions 3.1. Descriptive analysis Figure 1 depicts the consumer price index (inflation) of the selected countries and world oil price. The graphical plot of the three variables (CPI) shows an upward increasing trend in which the co-movement showed greater similarity starting from the beginning onwards. This graphical plot confirms the finding of Durevall and Sjö (2012). They found that inflation in both Ethiopia and Kenya has increasing patterns. The world oil price is more fluctuated over the given period than inflation. The price increased to higher values in 2008 and it does not show a clear trend which contrasts the finding of Ademe (2015). Domestic inflation of Ethiopia had a similar trend with that of world oil price. The fluctuation in oil prices led to the fluctuation of inflation. The oil prices which were higher will be immediately followed by the rising prices of oil products including gasoline and fuel oil, which were used by the consumer. The exchange rate of the three countries, generally, showed an increasing trend with high fluctuation (Figure 2). The fluctuation is low in the case of Ethiopia compared to the other countries. This low fluctuation may be due to the fact that Ethiopian exchange rate is characterized by a managed floating regime. Figure 1: Graphical representation of inflation Time in Month C P I( E th io p ia ) 2008 2012 2016 2 0 4 0 6 0 8 0 1 2 0 Time in Month C P I( K e n y a ) 2008 2012 2016 8 0 1 2 0 1 6 0 Time in Month C P I( S o u th A fr ic a ) 2008 2012 2016 6 0 8 0 1 0 0 Time in Month P ri c e o f O il 2008 2012 2016 4 0 8 0 1 2 0 Time in Month C P I( E th io p ia ) 2008 2012 2016 2 0 4 0 6 0 8 0 1 2 0 Time in Month C P I( K e n y a ) 2008 2012 2016 8 0 1 2 0 1 6 0 Time in Month C P I( S o u th A fr ic a ) 2008 2012 2016 6 0 8 0 1 0 0 Time in Month P ri c e o f O il 2008 2012 2016 4 0 8 0 1 2 0 Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 69 3.2. Tests of stationarity Augmented Dickey-Fuller (ADF) and Philips Perron (PP) tests were used to test the stationarity properties of the series. The summary of the result is given in Table 1a) and b). The result indicates that the null hypothesis of the presence of unit root has failed to reject at 5 percent level of significances. This implies that the series is not stationary at level. On the other hand, all the variables at 5 the percent level of significance are statistically significant in the first difference. We thus realize that all the series over time is stationary in first difference. Table 1a): ADF tests of stationary At a level At the first difference Variables Test Statistic Critical value at 5% P-values Test Statistic Critical value at 5% P-values Oil price -1.631 -2.888 0.4669 -5.279 -2.888 0.000 ETHEXR 0.690 -2.888 0.9896 -7.814 -2.888 0.000 ETHCPI 0.906 -2.888 0.9932 -5.772 -2.888 0.000 KEXR -1.419 -2.888 0.5732 -8.412 -2.888 0.000 KCPI 0.221 -2.888 0.9734 -6.425 -2.888 0.000 SEXR -0.527 -2.888 0.8867 -6.421 -2.888 0.000 SCPI 0.361 -2.888 0.9800 -8.068 -2.888 0.000 Source: Own computation results on sample data Table 1b): PP tests of stationarity Variables At a level At first difference Test Statistic Critical value at 5% P-values Test Statistic Critical value at 5% P- values Oil price -1.878 -2.888 0.3424 -7.480 -2.888 0.000 ETHEXR 0.546 -2.888 0.9862 -9.108 -2.888 0.000 ETHCPI 0.714 -2.888 0.9901 -7.808 -2.888 0.000 KEXR -1.138 -2.888 0.6997 -8.559 -2.888 0.000 KCPI -2.491 -2.888 0.1176 -10.901 -2.888 0.000 SEXR -1.225 -2.888 0.6629 -21.732 -2.888 0.000 SCPI 0.707 -2.888 0.9900 -8.405 -2.888 0.000 Source: Own computation results on sample data Figure 2: Exchange rate of the selected countries Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 70 3.3. Optimal lags determination Table 2 reports optimal lags order selection statistics. In this Table the minimum values from each of the information criteria are given by star sign (*).The result shows the optimal lag length is one. So, we precede further tests and estimations with lag (1). Hence, the VAR (p) and VECM (P) models which are used are VAR (1) and VECM (1). 3.4. Co-integration analysis Having confirmed the existence of unit root at a level in the series in Table 1, co-integration tests were conducted by Johansson test of co-integration. Table 3 reports the co-integration analysis outputs. The result shows that the trace test didn’t reject the null hypothesis of zero co-integrating vector at 5% level of significance (22.2364*) in Kenya in favor of at most one co- integrating vectors in case of Ethiopia and South Africa (13.8785* and 11.7716*) respectively. Therefore, the computed trace statistics that are greater than the critical trace values at a 5 percent level of significance explains the rejection of the null hypothesis of zero co- integrating vectors. This implies that inflation in the case of Ethiopia and South Africa has a long run relationship with respective to their exchange rate and world oil prices. 3.5. Estimation of the Vector Autoregressive (VAR) Model Table 4 comprises the result of inflation dynamics computed by using VAR model. The computed values indicate that the past value of the endogenous variable information in Ethiopia is positive significant effect in determining its own current values (33.76%) at five percent significant levels. From the results, it is also clearly inferred that the past values of inflation in Kenya (93.74%) and other constant variables (35.42%) have significant effect in determining the current values of inflation in Ethiopia keeping other variables constant. For the equation of inflation in Kenya, the past values of KCPI and SCPI have positive significant effect on the current values of KCPI at five significant levels. 3.6. Vector error correction model estimation The presence of co-integration suggests a long run relationship among the variables under consideration. To discuss the long run equilibrium relations and short- run adjustment processes, the researcher estimated vector error correction model. The long run relationship and short-run adjustment processes among inflation, exchange rates and world oil price for 1 co-integrating vector for Ethiopia are shown in Table 5. The coefficients of exchange rate and world oil price at the first lag were significant at 5% level of significance. From the Table, it is inferred that there was no long-run causality between inflation and its first lag. When we consider the first equation (inflation) the coefficient error correction term values are non-negative and not significant. The values do not confirming long run causality. The coefficient of error correction term of exchange rate equation and world oil prices equation values are negative and significant at 5%. The coefficient values are -22.58 and -27.08 percent monthly, meaning that the system corrects the previous period disequilibrium at a speed of 22.58 and 27.08, respectively. The error correction term which is the normalized co-integrating equation obtained from the VEC model is as follows: Table 2: Optimal Lags Determination Source: Own computation results on sample data Lag LL LR df p FPE AIC HQIC SBIC 0 -1555.630 55.835 23.888 23.950 24.041* 1 -1471.540 172.190 49 0.000 31.726* 23.321 23.821* 24.550 2 -1424.500 94.079 49 0.000 32.886 23.351 24.288 25.656 3 -1377.370 94.258 49 0.000 34.365 23.380 24.753 26.760 4 -1341.740 71.262* 49 0.021 43.416 23.584 25.394 28.039 ΔETHCPI = -45808 ΔETHEXR + 0.3035 ΔWorld oil price – 144395 Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 71 Table 3: Johansson Co-integration Tests Johanson Co-integration Tests in case of Ethiopia (ETHCPI,ETHEXR and World oil price) Maximum Trace 5% critical Rank Parms LL Eigenvalue Statistic value 0 3 -671.7423 . 38.8071 29.68 1 7 -659.278 0.0589 13.8785* 15.41 2 11 -653.23229 0.0582 1.7871 3.76 3 12 -652.33874 0.01315 Johansson Co-integration Tests in case of Kenya (KCPI,KERT and World oil price) Maximum Trace 5% critical Rank Parms LL Eigenvalue Statistic value 0 3 -855.7808 22.2364* 29.68 1 7 -848.1779 0.1073 7.0305 15.41 2 11 -844.6693 0.0510 0.0132 3.76 3 12 -844.6693 0.0001 Johansson Co-integration Tests in case of South Africa (SCPI, SEXR and World oil price) Maximum Trace 5% critical Rank Parms LL Eigenvalue Statistic value 0 3 -551.944 . 39.0134 29.68 1 7 -538.323 0.184 11.7716* 15.41 2 11 -532.444 0.084 0.0124 3.76 3 12 -532.438 0.000 Johansson Co-integration Tests of Inflation across the Sampled Countries Maximum Trace 5% critical Rank Parms LL Eigenvalue Statistic value 0 3 -412.5450 . 19.7748* 29.68 1 7 -405.3309 0.10136 5.3466 15.41 2 11 -403.4722 0.0272 1.6291 3.76 3 12 -402.6576 0.0120 Source: Own computation results on sample data Table 4: Output of VAR model for inflation of the sampled countries Coef. Std. Err. Z P>z [95% Conf. Interval] D_ETHCPI ETHCPI- LD KCPI-LD. SCPI- LD. Cons 0.3376 0.9374 0.0780 0.3542 0.0844 0.0387 0.2615 0.1384 4.00 24.17 0.30 2.56 0.000 0.000 0.766 0.011 0.1722 0.8614 -0.4345 0.0829 0. 5030 1.0134 0.5904 0.6256 D_KCPI ETHCPI -LD KCPI-LD. SCPI-LD. Cons -0.0130 0.4880 0.5851 0.2210 0.0719 0 .0731 0.2228 0.1180 -0.18 6.68 2.63 1.87 0.857 0.000 0.009 0.061 -0.1539 0. 3138 0.1483 -0.0101 0.1279 0.6312 1.0219 0.4523 D_SCPI ETHCPI-LD. KCPI-LD. SCPI-LD. Cons 0.0311 0.0268 0.2681 0.2615 0.0280 0.0285 0.0870 0.0460 1.11 0.94 3.08 5.68 0.268 0.347 0.002 0.000 -0.0239 -0.0290 0.0976 0.1712 0.0861 0.0827 0.4387 0.3518 Source: Own computation results on sample data Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 72 According to normalized equation, exchange rate and world oil price contributes to inflation in the long- run. Table A-2 (appendix) reports the VEC output of inflation in South Africa. The result shows that the coefficients of error correction terms are significant at 5% significant level. As understood from the VECM model results, exchange rate contributed negatively in the long run to the inflation in Ethiopia and South Africa. That is, contribute negatively to decrease the exchange rate aggravated inflation of the mentioned country. Conversely, world oil price contributes to inflation positively in the long run in case of Ethiopia and but negatively to that of South Africa. The increase in oil prices led to rising inflation and vice versa, which contrasts the finding of Sek et al. (2015). The study found that oil prices have a considerable effect on domestic prices in developing countries which are highly oil dependent. 3.7. Granger causality tests Recall that even though a co-integration test shows long run relationship among variables, it does not specify the direction of a causal relation. Chi-square statistics and probability values constructed under the null hypothesis is rejected if the probability value is more than 5% significance level. Table 6 provides the VAR & VEC Granger Causality tests results. VEC- Granger causality analyses of inflation, exchange rate, and world oil price in case of Ethiopia provides the existence of unidirectional causality running from the world oil price to inflation at the 5% significance level (0.0021). Moreover, there is unidirectional causality running from the joint exchange rate and world oil price to inflation. This evinces that past values of joint world oil price and exchange rate enabled to predict the present values of inflation. In the case of South Africa, the VEC Granger causality/block exogeneity Wald tests indicate the existence of unidirectional causality running from world oil price to inflation at 5% of significance level. These results are in agreement with the finding of Brahmasrene et al., (2014). They documented that any changes in international oil price will cause a change in inflation. Similarly, the VAR granger causality Wald tests results regarding inflation in the sampled countries show the unidirectional granger causality running from inflation in Southern Africa to inflation in Kenya. This implies that in the short run inflation in South Africa is one of the driving forces of inflation in Kenya in addition to other macro-economic variables. In addition, unidirectional granger causality running from inflation in Kenya to Ethiopia was observed. World oil price has no equal contribution for the inflation fluctuation across the selected countries. Table 5: output of VECM in case of Ethiopia Coef. Std. Err. Z P>z [95% Conf. Interval] D_ETHCPI CE1_1 0.0071 0.0100 0.72 0.474 -0.0124 0.0267 Cons 0.7240 0.0871 8.32 0.000 0.5531 0.8946 D_ETHEXR CE1_2 -0.2258 0.0881 -2.56 0.010 -0.0532 -0.3984 Cons 0.1376 0.028713 4.79 0.000 0.0813 0.1938 D_Oil price CEl_3. -0.2708 0.0602 -4.50 0.000 -0.3888 -0.1528 Cons 0.0181 0.5259 0.03 0.973 -1.0128 1.0490 Johansen normalization restriction imposed Beta Coef Std. Err. Z P>|z| [95% Conf. Interval] ETHCPI 1 ETHEXR -4.5808 0.3470 -13.20 0.000 -5.2609 -3.9007 Oil Price 0.3035 0.0685 4.43 0.000 0.1692 0.4377 Cons -14.4395 Source: Own computation results on sample data Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 73 Table 6: VAR &VEC granger causality tests results VEC Granger Causality/Block Exogeneity Wald Tests in case of Ethiopia Equation Excluded chi2 Df Prob>chi2 D.ETHCPI D.Ethexr 0.1940 1 0.6596 D.Oil price 9.4180 1 0.0021 All 9.5626 2 0.0084 D.ETHEXR D. ETHCPI 0.0230 1 0.8796 D.Oil price. 0.1560 1 0.6929 All 0.2653 2 0.8758 D.Oil price D.ETHEXR 0.1195 1 0.7295 D. ETHCPI 0.1769 1 0.6741 All 0.3105 2 0.8562 VEC Granger Causality/Block Exogeneity Wald Tests in case of South Africa Equation Excluded chi2 Df Prob>chi2 D. SCPI D. SEXR 2.5478 1 0.1104 D.Oil price 8.648 1 0.0033 All 11.7925 2 0.0027 D. SEXR D. SCPI 0.9112 1 0.3398 D.Oil price. 8.0359 1 0.0046 All 10.7764 2 0.0046 D. Oil price D. SCPI 0.8433 1 0.3585 D. SEXR 0.0492 1 0.8244 All 1.0237 2 0.5994 VAR Granger Causality/Block Exogeneity Wald Tests in case of Kenya Equation Excluded chi2 Df Prob>chi2 D. KCPI D. KEXR 2.3925 1 0.1219 D.Oil price 3.2667 1 0.0707 All 4.0564 2 0.1317 D. KEXR D. KCPI 3.6663 1 0.0555 D.Oil price. 0.2595 1 0.6105 All 4.7924 2 0.0911 D. Oil price D. KCPI 0.3027 1 0.5822 D. KEXR 1.3963 1 0.2373 All 3.8442 2 0.1463 VAR Granger Causality/Block Exogeneity Wald Tests of inflation in case of Selected Countries Equation Excluded chi2 Df Prob>chi2 D. ETHCPI D. KCPI 6.1847 1 0.0194 D. SCPI 0.0889 1 0.7660 All 2.0275 2 0.3630 D. KCPI D. ETHCPI .03252 1 0.8570 D. SCPI. 6.8917 1 0.0090 All 7.2409 2 0.0270 D. SCPI D. ETHCPI 1.2269 1 0.2680 D. KCPI 0.8835 1 0.3470 All 3.8442 2 0.1463 Source: Own computation results on sample data 3.8. Impulse response function An impulse response function traces the effect of a one-time shock to one of the innovations on current and future values of the endogenous variables. Figure 3 displays the estimated impulse response of inflation in Ethiopia toward the change of world oil price and Ethiopian Birr/USA Dollar exchange rate. The figure reveals that inflation responds positively over the whole period with slightly increasing when a positive shock given to an exchange rate, which supports the finding of Habtamu Getnet (2015). He has found that the exchange rate has a direct effect on the increments or decrements Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 74 of domestic inflation of Ethiopia. Figure 4 reports the estimated VAR impulse response function of inflation across the sampled countries. The result shows a one standard error shock of Ethiopian inflation positively influenced Kenyan’s inflation, but a positive shock of the inflation in Kenya affected the inflation in Ethiopia negatively. From this, it is evident that when there is positive shock to Ethiopia’s inflation, inflation in Kenya is increasing. Nevertheless, the inflation in Ethiopia decreases if Kenya’s inflation gets a shock. It also understood that a greater real trade integration and border ties could increase the sensitivity of inflation to cross border shocks. Figure A-1 (annex) shows that the impulse response function of inflation dynamics in Kenyan to Shilling/ USA Dollar exchange rate and world oil price. The figure reveals that the response of inflation to a unit standard deviation shock to exchange rate is positive and almost with increasing movements which contrasts the finding of Okara and Mutuku (2019). They found that a shock given to exchange rate has negative effects on inflation. Also, the response of inflation to a unit standard deviation shock to world oil price is positive. In other words, when there is a positive innovation given to exchange rate and oil price increases the inflation in that country. Figure A-2 (annex) exhibits impulse response function of inflation in South Africa towards Rand/USA Dollar exchange rate and world oil price received. The plot shows that the response of inflation in South Africa was positive when exchange rate faced a shock. Exchange rate shocks had a similar positive effect on inflation in both Ethiopia and Kenya, yet negative in South Africa. The response of inflation towards the world oil price is similar in all selected countries over the given time horizon. Furthermore, the response of inflation for itself innovation has little effect for the selected countries. 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to ETHCPI 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to ETHEXR 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to OIL .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of ETHEXR to ETHCPI .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of ETHEXR to ETHEXR .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of ETHEXR to OIL -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to ETHCPI -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to ETHEXR -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to OIL Response to Nonfactorized One S.D. Innovations Figure 3: Impulse response functions of inflation in case of Ethiopia Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 75 -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to ETHCPI -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to KCPI -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 Response of ETHCPI to SCPI -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to ETHCPI -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to KCPI -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to SCPI -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 Response of SCPI to ETHCPI -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 Response of SCPI to KCPI -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 Response of SCPI to SCPI Response to Cholesky One S.D. Innovations ± 2 S.E. Figure 4: VAR Impulse Response Function of Inflation across the selected countries 4. Conclusions This study empirically presents the comparative view of inflation dynamics among three African countries. Even though the main driving forces of high inflation across the sampled countries varies, the exploratory analysis of monthly data spanning from January 2007 to April 2018 shows the inflation trend is similar in the long run. The result of Johansen Co- integration test revealed that the CPI, exchange rates and oil price have co-integration relationship in Ethiopia and South Africa case. In the long run, inflation in both countries is driven by exchange rates and world oil price. Exchange rates have positively significant effects on inflation dynamics of both countries while world oil price contributes positively in Ethiopia but negatively in South Africa. In the short run, inflation in Kenya has a predicting power about inflation in Ethiopia and inflation in South Africa has a predicting power about inflation in Kenya. On the other hand, inflation in Kenya and Ethiopia do not have a predicting power about inflation in South Africa. Furthermore, the outcome of impulse response function demonstrates that exchange rates and oil price shocks affects inflation dynamics of the sampled countries at different stages both directly as well as indirectly. Shocks to inflation in South Africa have positive impact on inflation in Ethiopia while shocks to inflation in Kenya have negative in the short run. Inflation across the sampled countries has no long run interactive relationship. There are numerous policy implications that can be drawn from this analysis. First, there is growing evidence that exchange rates are a driving force for high inflation for the selected countries. So, establishment of Monitory union is recommended to stabilize this high inflation variability by managing exchange rate variability. Second, fluctuation of oil price is also observed as it is a driving force of high inflation. Low income countries like Ethiopia and Kenya are unlikely to have the resources to have stocks to take advantage of periods of low prices or insurance against rises, so that they will be affected by price increases. Therefore, Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 76 it is a mandatory for the interference of central bank to stabilize the high variability of oil price by taking into account those countries. Finally, increased economic and trade integrity is likely to lead greater sensitivity of aggregate inflation dynamics to costs of imported inputs, especially when cost changes are large in magnitude. This issue should be a concern of macroeconomic policies coordination because no single country can on its own assure stability to the international economic system. Annex: Table A-1: The output of VAR (1) in the case of Kenya Coef. Std. Err. Z P>z [95% Conf. Interval] D_KCPI KCPI |LD. 0.5255 0.0720 7.30 0.000 0.3830 0.6679 KEXR |LD. 0.0241 0.0384 0.63 0.532 -0.0518 0.1000 oil |LD. 0.0187 0.0112 1.67 0.097 -0.0035 0.0410 _cons 0.4136 0.0921 4.49 0.000 0.2314 0.5958 D_kexr KCPI|LD. 0.0983 0.1610 0.61 0.542 -0.2201 0.4168 KEXR |LD. 0.2721 0.0858 3.17 0.002 0.1024 0.4418 oil |LD. -0.0237 0.0251 -0.94 0.348 -0.0733 0.0260 _cons 0.0885 0.2059 0.43 0.668 -0.3188 0.4958 D_oil KCPI | LD. -0.3095 0.5272 -0.59 0.558 -1.3526 0.7336 KEXR |LD. -0.4966 0.2809 -1.77 0.079 -1.0524 0.0592 oil | LD. 0.3541 0.0822 4.31 0.000 0.1915 0.5167 _cons 0.4250 0.6743 0.63 0.530 -0.9090 1.7589 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 Response of KEXR to KEXR -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 Response of KEXR to KCPI -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 Response of KEXR to OIL -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to KEXR -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to KCPI -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 Response of KCPI to OIL -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to KEXR -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to KCPI -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to OIL Response to Cholesky One S.D. Innovations ± 2 S.E. Figure A-1: Impulse Response Function of Inflation Dynamics in case of Kenya Appendix Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 77 Table A-2: Output of VECM in case of South Africa Coef. Std. Err. Z P>z [95% Conf. Interval] D_SCPI _ce1 |L1 -0.0063 0.0022 -2.84 0.004 -0.0107 -0.0020 _cons 0.4164 0.0280 14.89 0.000 0.3616 0.4713 D_SEXR _ce1 |L1 0.1087 0.0048 2.27 0.023 0.0015 0.0203 _cons 0.0354 0.0601 0.59 0.556 -0.0824 0.1532 D_oil _ce1 | L1. 0.1638 0.0427 3.83 0.000 0.0800 0.2475 _cons 0.0138 0.5359 0.03 0.979 -1.0365 1.0641 Johansen normalization restriction imposed Beta Coef Std. Err. Z P>|z| [95% Conf. Interval] _SCPI 1 SEXR -10.826 0.9508 -11.39 0.000 -12.6899 -8.9630 Oil -0.5498 0.0980 -5.61 0.000 -0.7418 -0.3577 _cons 64.1050 Source: Own computation results on sample data -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of SCPI to SCPI -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of SCPI to SEXR -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 Response of SCPI to OIL -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 Response of SEXR to SCPI -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 Response of SEXR to SEXR -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 Response of SEXR to OIL -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to SCPI -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to SEXR -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 Response of OIL to OIL Response to Cholesky One S.D. Innovations Figure A-2: Impulse Response Function of inflation in case of South Africa Reference Abounoori, A.A., Nazarian, R. & Amiri, A. (2014). Oil Price Pass-Through into Domestic Inflation: the Case of Iran. International Journal of Energy Economics and Policy, 4(4):662-669. Ademe AS (2015). Interaction of Ethiopian and World Inflation: A Time Series Analysis; TVECM Approach. Intel Prop Rights, 3(3): 147, doi:10.4172/2375-4516.1000147. Desa Daba. Ethiop.J.Sci.Sustain.Dev., Vol. 7 (2), 2020 78 Al-Shammari, N., & Al-Sabaey, M. (2012). Inflation Sources across Developed and Developing Countries; Panel Approach. International Business & Economics Research Journal, 11(2): 185-194. Anh, D.M.Nguyen, Jemma Dridi, Filiz D. Unsal, & Oral H. Williams (2017). On the Drivers of Inflation in Sub-Saharan Africa: International Economics, 151:71-84. Asghar, N., & Naveed, T. A. (2015). Pass-through of World Oil Prices to Inflation: A Time Series Analysis of Pakistan. Pakistan Economic and Social Review, 53(2):269-284. Brahmasrene, T., Huang, J. C., & Sissoko, Y. (2014). Crude Oil Prices and Exchange Rates: Causality, Variance Decomposition and Impulse Response. Energy Economics, 44: 407-412. Chou, K. W., & Tseng, Y. H. (2011). Oil Price Pass-through into CPI Inflation in Asian Emerging Countries. Journal of Economics,Finance and Management Sciences, 2(1):1-13 Christine Garnier, Elmar Mertens, & Edward Nelson (2015).Trend Inflation in Advanced Economies. International Journal of Central Banking, 11(4): 65-136 Dick Durevall, Loening, J.L., & Yohannes Ayalew (2012). Inflation Dynamics and Food Prices in Ethiopia. Journal of Development Economics, 104: 89–106 Durevall, D., & Sjö, B. (2012). The Dynamics of Inflation in Ethiopia and Kenya. Working Paper Series N 151 African Development Bank, Tunis, Tunisia Eickmeier,S.,& Kühnlenz, M. (2018).China's Role in Global Inflation Dynamics. Macroeconomic Dynamics, 22(2): 225-254. Habtamu Getnet (2015). Modeling the Growth of Ethiopian Inflation and Its Dynamic Behavior over Time. Global Journal of Human-Social Science, 15 (7): 2249-460x & Print ISSN: 0975-587X Gudina Goda, Destaw Akele, & K. Rajan (2018).The Effect of Devaluation on Domestic Prices in Ethiopia. American Journal of Economics, 8(4):191-201 Gujarati, D.N. (2004). Basic Econometrics (Fourth Edition). New York: McGraw Hill Book Co., 817-820. Kargi, B. (2014). The Effects of Oil Prices on Inflation and Growth: Time Series Analysis in Turkish Economy for 1988:01- 2013:04 Period. International Journal of Economics and Research, 2(5):29-36. Kavila, W., & Le Roux, P. (2016). Inflation Dynamics in a Dollarized Economy: The Case of Zimbabwe. Southern African Business Review, 20(1):94-117. Misati, R. N., Nyamongo, E. M., & Mwangi, I. (2013). Commodity Price Shocks and Inflation in a Net Oil-Importing Economy. Organization of the Petroleum Exporting Countries (OPEC Energy Review), 37(2):125-148 Okara, V.M., & Mutuku, C. (2019). Selected Macroeconomic Drivers of Inflation in Kenya. Research Journal of Economics, 3(1) Romer David (2012). Advanced Macroeconomics (Fourth Edition). New York, McGraw-Hill, a business unit of The McGraw- Hill Companies, pp513-583 Sek, S. K., Teo, X. Q., & Wong, Y. N. (2015). A Comparative Study on the Effects of Oil Price Changes on Inflation. Procedia Economics and Finance, 26: 630-636.