Frontiers in Computing and Intelligent Systems ISSN: 2832-6024 | Vol. 3, No. 1, 2023 1 Prediction of Telecom Customer Churn Based on MIPCA-XGBoost Method Chen Zhuo* School of Control and Computer Engineering, North China Electric Power University, Beijing 102200, China * Corresponding author Email: cherrybombczz@163.com Abstract: In order to solve the problem that the nonlinear information of data in the field of telecom customer churn prediction is not fully used, or even ignored, which leads to inaccurate prediction, this paper introduces the mutual information feature selection method (MIPCA) to filter the features and reduce the dimensions of customer data, and proposes an XGBoost method based on the mutual information feature selection method(MIPCA-XGBoost), which improves the accuracy of the prediction results. By using the data set of telecom industry customers published on Kaggle website, compares the prediction result of this method with that of machine learning algorithms commonly used in this field, and proves the accuracy, recall and F_Score of MIPCA-XGBoost method is higher than other algorithms. Keywords: Customer churn; Telecom customers; Mutual information feature selection; XGBoost algorithm. 1. Introduction Nowadays, the market of China's telecom industry is becoming increasingly saturated, the competition between enterprises is becoming more and more fierce, and the customer churn rate is gradually rising. Many enterprises focus on how to use novel marketing models to attract new customers and further develop them into loyal customers. However, studies show that the cost of time and money required for a company to develop a new customer is far greater than the cost of maintaining an existing customer [1]. Therefore, it is imperative for enterprises to build a model that can accurately predict the customer churn tendency, understand the customer churn tendency in time and adjust the customer maintenance strategy to reduce the customer churn rate. Customer churn is a complex problem, and the prediction methods for different industries are different. At present, there are a large number of domestic literatures on customer churn, involving a wide range of fields. Zhang Lili [2] and others used decision tree algorithm to predict airline customer churn, and successfully improved the seating rate; Yan Chun [3] and others used BP-Adaboost algorithm to predict the clustered life insurance industry customers, providing a higher prediction accuracy; In the field of e-commerce, Wu Yongchun [4] fused multiple methods to establish a prediction model, which shortened the prediction time. However, the customer data in the telecommunications industry has the characteristics of large quantity and high dimension. Although the above research has made important contributions to the research on customer churn prediction in the fields of aviation, life insurance, e-commerce and so on, it does not mine the important features of the data set, resulting in information redundancy and even dimension disaster [5], which will have an impact on the customer churn prediction in the telecommunications industry and reduce its prediction efficiency and accuracy. At present, the data feature selection in the field of customer churn prediction is generally based on the traditional statistical principal component analysis and linear discriminant method [6]. Its advantages are that the theoretical basis is solid and the method is simple and easy to operate, but the nonlinear relationship between attributes is ignored, the information is not fully utilized, and even important information is lost. The mutual information feature selection method can retain most of the original information while effectively reducing the dimension, and take into account the nonlinear relationship between variables [7]. In addition, XGBoost algorithm has full application in short- term photovoltaic power generation prediction [8-11], flight delay prediction [12-14], food safety risk prediction [15-18] and other prediction fields. These studies show that XGBoost has the advantages of high flexibility, fast execution speed, and high accuracy of prediction results. Based on this, this paper proposes an XGBoost prediction method based on mutual information feature selection to solve the problem of customer churn in the telecommunications industry, and compares the accuracy, recall, and F_ Score and other indicators, and the analysis proves the effectiveness of the method proposed in this paper in telecom customer churn prediction. 2. MIPCA-XGBoost customer churn prediction method 2.1. MIPCA method In information theory, mutual information is a measure of interdependence between random variables, which can also be understood as the amount of information of another random variable contained in one random variable [11]. In feature selection, the principal component analysis method in traditional statistics is to analyze the linear relationship between two variables, but cannot reflect the nonlinear relationship in the data. Therefore, this paper considers introducing mutual information to feature selection, which is very helpful for evaluating the interdependence between variables, and is no longer limited to the linear relationship. Here we introduce information entropy H, which is used to represent the uncertainty of a random variable. Suppose there are random variables X and Y in data set M, and there are joint distributions ๐‘(๐‘ฅ, ๐‘ฆ) and marginal distributions ๐‘(๐‘ฅ) and ๐‘(๐‘ฆ), then there are 2 ๐ป(๐‘‹, ๐‘Œ) = ๐ป(๐‘‹) + ๐ป(๐‘Œ|๐‘‹) = ๐ป(๐‘Œ) + ๐ป(๐‘‹|๐‘Œ) (1) Where, ๐ป(๐‘‹|๐‘Œ) and ๐ป(๐‘Œ|๐‘‹) are conditional information entropy, which represents the information entropy of its own information after deducting other conditions, which can be expressed as ๐ป(๐‘‹|๐‘Œ) = โˆ’ โˆ‘ ๐‘(๐‘ฅ, ๐‘ฆ)๐‘™๐‘œ๐‘”๐‘(๐‘ฅ|๐‘ฆ)๐‘ฅโˆˆ๐‘‹ (2) ๐ป(๐‘Œ|๐‘‹) = โˆ’ โˆ‘ ๐‘(๐‘ฅ, ๐‘ฆ)๐‘™๐‘œ๐‘”๐‘(๐‘ฆ|๐‘ฅ)๐‘ฆโˆˆ๐‘Œ (3) For random variables X and Y, the amount of information of another variable contained in one variable can be expressed by mutual information [11], which is defined as ๐ผ(๐‘‹, ๐‘Œ) = ๐ป(๐‘‹) โˆ’ ๐ป(๐‘‹|๐‘Œ) = ๐ป(๐‘Œ) โˆ’ ๐ป(๐‘Œ|๐‘‹) (4) The information entropy of random variables X and Y can be expressed as ๐ป(๐‘‹) = โˆ’ โˆ‘ ๐‘(๐‘ฅ)๐‘™๐‘œ๐‘”๐‘(๐‘ฅ)๐‘ฅโˆˆ๐‘‹ (5) ๐ป(๐‘Œ) = โˆ’ โˆ‘ ๐‘(๐‘ฆ)๐‘™๐‘œ๐‘”๐‘(๐‘ฆ)๐‘ฆโˆˆ๐‘Œ (6) Therefore, we can further obtain the mutual information ๐ผ(๐‘‹, ๐‘Œ) of random variables X and Y as ๐ผ(๐‘‹, ๐‘Œ) = โˆ‘ โˆ‘ ๐‘(๐‘ฅ, ๐‘ฆ)๐‘™๐‘œ๐‘” ๐‘(๐‘ฅ,๐‘ฆ) ๐‘(๐‘ฅ)๐‘(๐‘ฆ)๐‘ฆโˆˆ๐‘Œ๐‘ฅโˆˆ๐‘‹ (7) In the principal component analysis method, the mutual information matrix is used to replace the covariance matrix, and the relationship between the eigenvector and the eigenvalues of the mutual information feature selection method is obtained as ๐ด๐‘‡ ๐›ด๐ผ ๐ด= ๐ต (8) Among them, ๐›ด๐ผ is the mutual information matrix corresponding to the data set M, ๐ด is the matrix formed when the eigenvector of the mutual information matrix is a column vector, and ๐ต is the eigenvalue matrix of the mutual information matrix. In ๐›ด๐ผ , the elements on the diagonal represent the self-information of variables, while the elements on the non-diagonal represent the mutual information of variables. When the two variables are not related, the mutual information is 0. The principal component ๐‘ of mutual information matrix ๐›ด๐ผ is ๐‘๐‘˜ = ๐›ผ๐‘˜ ๐‘‡๐‘ฅ (9) Among them, ๐›ผ๐‘˜ ๐‘‡(๐‘˜ = 1,2, . . . , ๐‘›) โˆˆ๐ด๐‘‡ , is conversion coefficient of ๐‘๐‘˜ . Define the contribution rate of the kTH feature as ๐œŽ๐‘˜. The formula ๐œŽ๐‘˜ = ๐œ‡๐‘˜ โˆ‘ ๐œ‡๐‘˜ ๐‘› ๐‘˜=1 (10) ๐œ‡๐‘˜ is the ๐‘˜ TH largest eigenvalue of the mutual information matrix. In this paper, the first m principal components whose cumulative contribution rate of ๐›ฝ is about 90% are selected as the output of the feature selection results, and the dimensionality reduction of the data set is realized. 2.2. Principles of XGBoost model XGBoost algorithm is a model that uses CART tree as the base learner for training and combines multiple base learners to construct a strong classifier. XGBoost is used to train the data set, divide the sample data into each leaf node according to different classification characteristics, calculate the gain value of the tree model before and after classification, and finally obtain a training model with the minimum loss value. The objective function can be expressed as ๐‘‚๐‘๐‘— = โˆ‘ ๐‘™(๐‘ฅ, ๐‘ฅ๏ฟฝฬ‚๏ฟฝ) + โˆ‘ ฮฉ(๐‘“๐‘ก)๐‘‡ ๐‘ก=1 ๐‘› ๐‘–=1 (11) Where ๐‘™ is the loss function, ๐‘ฅ๐‘– is the true value of the i- th sample data, ๐‘ฅ๏ฟฝฬ‚๏ฟฝ is the predicted value of the ith sample, n is the total number of samples, ฮฉ(๐‘“๐‘ก) is the penalty term controlling the complexity of the model in the t th tree, and T is the number of training trees. XGBoost is a superposition training model. When training the t-th tree, the objective function of the t-th tree is ๐‘‚๐‘๐‘—๐‘ก = โˆ‘ ๐‘™ (๐‘ฅ๐‘– , ๐‘ฅ๏ฟฝฬ‚๏ฟฝ (๐‘กโˆ’1) + ๐‘“๐‘ก(๐‘ฅ๐‘–)) + ฮฉ(๐‘“๐‘ก) + ๐‘๐‘› ๐‘–=1 (12) ๐‘“๐‘ก(๐‘ฅ๐‘–) = ๐‘ค๐‘ž(๐‘ฅ๐‘–) (13) Where, ๐‘“๐‘ก(๐‘ฅ๐‘–) is the weight of sample ๐‘ฅ๐‘– in the t-th tree, and its formula is shown in Equation (13), c is a constant, ๐‘ž(๐‘ฅ๐‘–) is the position of the ith sample on the t-th tree, which is specifically represented by the number of leaf nodes it falls on, and ๐‘ค๐‘ž(๐‘ฅ๐‘–) represents the weight of the leaf node. The second-order Taylor series is used to expand the loss function, and the objective function after processing is ๐‘‚๐‘๐‘—๐‘ก = โˆ‘ [๐บ๐‘˜๐‘ค๐‘˜ + 1 2 (๐ป๐‘˜ + ๐œ†)๐‘ค๐‘˜ 2] + ๐›พ๐พ๐พ ๐‘˜=1 (14) โˆ‘ ๐‘”๐‘– = ๐บ๐‘˜๐‘–โˆˆ๐ผ๐‘˜ (15) โˆ‘ โ„Ž๐‘–๐‘–โˆˆ๐ผ๐‘˜ = ๐ป๐‘˜ (16) Where, ๐ผ๐‘˜ represents all samples falling on the kTH leaf node, and ๐‘”๐‘– and โ„Ž๐‘– are the replacements of the first and second derivatives of the loss function respectively. For each sample that has been trained t-1 times, its g and h are known. ๐บ๐‘˜ and๐ป๐‘˜ are the sum of g and h of all samples on k leaf nodes respectively. By observing the simplified objective function formula, it can be seen that this is a quadratic equation with one variable, and the extreme value is ๐‘คโˆ— = โˆ’ ๐บ๐‘˜ ๐ป๐‘˜ + ๐œ† (17) By substituting the extreme value into equation (14), the expression of leaf nodes in the tree to be trained can be written as ๐‘‚๐‘๐‘— = โˆ’ 1 2 โˆ‘ ๐บ๐‘˜ 2 ๐ป๐‘˜ + ๐œ† ๐พ ๐‘˜=1 + ๐›พ๐พ (18) XGBoost model calculates the Gain value by calculating ๐‘‚๐‘๐‘—๐‘‚๐ฟ๐ท โˆ’ ๐‘‚๐‘๐‘—๐‘๐ธ๐‘Š: ๐บ๐‘Ž๐‘–๐‘› = 1 2 [ ๐บ๐ฟ 2 ๐ป๐ฟ + ๐œ† + ๐บ๐‘… 2 ๐ป๐‘… + ๐œ† โˆ’ (๐บ๐ฟ + ๐บ๐‘…)2 ๐ป๐ฟ + ๐ป๐‘… + ๐œ† ] โ€“ ๐›พ (19) The higher the gain score, the higher the feature importance score of the split node, and the more important its corresponding feature. 2.3. MIPCA-XGBoost step The procedure is as follows: 1)Feature screening was performed on the data set by MIPCA method, and the first m principal components were obtained as new features, and the dimensionality reduction of the initial data set was realized; 2)Randomly divide the new data set after feature selection processing, and the divided training set is used as the data input of the model, and the test set is used to verify the trained model. The flow chart of MIPCA-XGBoost is shown in Figure 1. 3 Telecom customer data set MIPCA decomposition Deaverage Build sample mutual information matrix ่ฎก็ฎ—็‰นๅพๅ€ผไธŽ็‰นๅพๅ‘้‡ Select principal components Import XGBoost Set initial parameters Data training Test set prediction Output results Whether the maximum number of iterations has been reached No Yes Fig. 1 The flow chart of MIPCA-XGBoost method 3. Data preparation 3.1. Experimental data The telecom industry customer data set used in this paper has 48,712 pieces of data, including 9876 pieces of lost data and 38,836 pieces of non-lost data. The amount of lost data is about 20% of the total data set. In the experiment, the data set is randomly divided into 40% test set and 60% training set, which comes from Kaggle website. Each piece of data in the data set includes 57 characteristics and attributes, such as account opening time, remaining accounts, recharge period, online duration, and total call duration. Some attributes are shown in Table 1. Table 1. Part properties of dataset Data classification Data attributes Basic Information Customer ID, age, package, account opening time Billing information Account balance, recharge period, credit limit, etc Network duration Time spent online, time spent online on weekdays, time spent online on weekends, etc Communication information Number of calls, total call duration, number of calls, number of calls, etc Network Usage information Uplink traffic, downlink traffic, traffic overflow, etc Status of complaints The number of complaints, the response time of complaints, etc The data is preprocessed, 0 is used to fill the missing values in the data attributes, unique thermal coding is adopted for discrete attributes, and standardization is carried out for continuous attributes, so that the processed data can meet the standard normal distribution. 3.2. Feature selection MIPCA method was used to select the feature of the data set, and the feature selection results of the data set were compared with the principal component analysis method. The comparison results were expressed as the principal component characteristic value ฮผ and the cumulative contribution rate ฮฒ, as shown in Table 2. Table 2. Principal component eigenvalue and cumulative contribution rate Principal component PCA MIPCA ๐œ‡ ๐›ฝ ๐œ‡ ๐›ฝ PC1 16.34 30.07% 22.23 43.30% PC2 8.56 46.87% 8.34 56.67% PC3 5.23 57.13% 4.27 64.71% PC4 4.12 65.22% 3.68 70.35% PC5 2.85 69.81% 2.64 76.75% PC6 2.21 73.15% 1.93 80.65% PC7 1.80 76.68% 1.43 83.77% PC8 1.48 79.59% 1.04 86.34% PC9 1.23 82.64% 0.84 88.76% PC10 1.01 84.76% 0.65 89.93% PC11 0.88 85.60% 0.63 91.14% PC12 0.76 85.72% 0.57 92.22% PC13 0.64 86.43% 0.54 93.27% PC14 0.64 87.14% 0.49 94.12% PC15 0.62 87.80% 0.44 95.03% PC16 0.58 88.47% 0.37 95.87% PC17 0.56 89.22% 0.34 96.21% PC18 0.55 89.75% 0.32 96.54% PC19 0.55 90.28% 0.29 96.84% From the extraction results of principal components in Table 2, it can be seen that MIPCA has a higher cumulative contribution rate when principal components of the same dimension are selected. For example, to achieve a cumulative contribution rate of 90%, PCA method needs to select 19- dimensional principal components, while MIPCA method reduces the value to 11-dimensional, which indicates that MIPCA method can make full use of nonlinear information. Thus, the original information can be retained to a greater extent, which is helpful to improve the accuracy of subsequent prediction. In this paper, when the cumulative contribution rate reaches 90%, the first 11 dimensional principal components screened by MIPCA method are selected for XGBoost customer loss prediction. 4. Customer churn forecast 4.1. Evaluation index According to the confusion matrix, the prediction accuracy ๐ธ๐‘Ž๐‘๐‘ , the recall rate ๐ธ๐‘Ÿ๐‘’๐‘๐‘Ž๐‘™๐‘™ , and the ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ were calculated as the evaluation index of the algorithm. The calculation formula of each evaluation index is shown as follows, and the classification of customer state prediction results [12] is shown in Table 3. Table 3. Customer status classification True customer status Loss of prediction results The prediction result is not churn Actual loss TP FN Actual non- churn FP TN ๐ธ๐‘Ž๐‘๐‘ = ๐‘‡๐‘ƒ+๐‘‡๐‘ ๐‘‡๐‘ƒ+๐‘‡๐‘+๐น๐‘ƒ+๐น๐‘ (20) ๐ธ๐‘Ÿ๐‘’๐‘๐‘Ž๐‘™๐‘™ = ๐‘‡๐‘ƒ ๐‘‡๐‘ƒ+๐น๐‘ (21) 4 ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ = 2ร—๐‘‡๐‘ƒ 2ร—๐‘‡๐‘ƒ+๐น๐‘ƒ+๐น๐‘ (22) 4.2. Important parameter Settings of XGBoost algorithm The experiment running environment in this paper is a 64- bit Windows10 operating system, and the specific hardware Settings are as follows: 16 GB memory and 12th Gen Intel(R) Core(TM) i5-12490F @ 3.00 GHz CPU. python3 and related toolkits were used in the experiments. After many experiments, the parameters of XGBoost are finally set in Table IV. Table 4. The important parameters of XGBoost Parameter Parameter configuration max-depth 5 min-child-weight 3 learning-rate 0.3 gamma 0.1 subsample 0.76 n-estimators 200 4.3. Analysis of prediction results In this paper, MIPCA-XGBoost algorithm is applied to customer churn prediction in the telecom industry, and random forest and logistic regression algorithms commonly used in this field are used for comparison experiments. The comparison results of precision, recall and ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ of related algorithms are shown in Table 5. Table 5. Comparison of prediction results of various algorithms(%) Type of Algorithm ๐ธ๐‘Ž๐‘๐‘ ๐ธ๐‘Ÿ๐‘’๐‘๐‘Ž๐‘™๐‘™ ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ RF 84.12 84.36 83.25 LR 81.43 83.03 80.13 XGBoost 86.37 84.58 84.73 MIPCA-XGBoost 90.56 90.23 89.64 Observing the prediction results of various algorithms in Table 5, on the whole, the accuracy of three methods of random forest, logistic regression and XGBoost is more than 80%, and the MIPCA-XGBoost algorithm has the highest score, with an accuracy of 90.56%, a recall rate of 90.23%, and a ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ value of 89.64%. The accuracy of the random forest algorithm is 84.12%, and the accuracy of the logistic regression algorithm is 81.43%, which indicates that the MIPCA-XGBoost method is more suitable for application in this field. Secondly, through the comparison of the XGBoost algorithm MIPCA-XGBoost algorithm, it can be seen that the MIPCA feature selection method improves the prediction accuracy of the XGBoost algorithm in this experiment, its accuracy is increased by 4.19%, the recall rate is increased by 5.65%, and the ๐น_๐‘†๐‘๐‘œ๐‘Ÿ๐‘’ value is increased by 4.91%. 5. Conclusion From the perspective of making full use of the original information of the data set, this paper introduces the mutual information feature selection method in the study of customer churn prediction in the telecom industry, and proposes the MIPCA-XGBoost method, which successfully improves the prediction accuracy. By selecting the telecom customer data set from Kaggle website for experiments, the results show that the prediction accuracy of MIPCA-XGBoost method is as high as 90.56%. It can be seen that the algorithm is helpful for the further research of customer churn prediction in the future, and provides a new idea for enterprises to solve the problem of customer churn, helping enterprises to be more targeted and accurate in formulating customer maintenance strategies. The research of this paper also has some shortcomings :1) At present, the rapid development of Internet communication has become an inseparable part of people's communication and contact. Under this impact, many users' communication behaviors will be affected by instant messaging tools. In the future, we will consider the third-party communication software and Internet platform data for research. 2) The data in this paper are from a single telecom industry customer data, and in the future, multiple operators in the same time period will be considered for joint research to make the research more comprehensive. 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