# Integrated Learning-Based Algorithm for Predicting Graduates’ Employment Mental Health

Authors: Chen Dongrui; Wang Shengjie; Wen Kate
Journal: Mathematical Problems in Engineering
 (2022)

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## Abstract

Adaboost is a mental health prediction method that utilizes an integrated learning algorithm to address the current state of mental health issues among graduates in the workforce. The method first extracts the features of mental health test data, and after data cleaning and normalization, the data are mined and analyzed using a decision tree classifier. The Adaboost algorithm is then used to train the decision tree classifier for multiple iterations in order to improve its classification efficiency, and a mental health prognosis model is constructed. Using the model, 2780 students in the class of 2022 at a university were analyzed. The trial results demonstrated that the strategy was capable of identifying sensitive psychological disorders in a timely manner, providing a basis for making decisions and developing plans for mental health graduate students.


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## Body

## 1. Introduction

With the rapid development of the economy and information technology in today’s society, university graduates not only enjoy the convenience brought about by social progress and development but they also face a variety of pressures and negative information that are pervasive in contemporary society. As a result, the mental health of many university graduates is worrisome, and the proportion of graduates with psychological problems is rising, which has a negative effect on the healthy development of university graduates. The percentage of college graduates who suffer from psychological disorders is increasing, which has numerous negative effects on their healthy development [1, 2].Workplace stress may result in mental health problems [3]. Currently, the number of graduates from Chinese colleges and universities is increasing annually, and employers’ expectations of their employees’ overall skillsets are also rising, putting graduates under greater pressure to find employment. After more than ten years of carefree education, graduates must adjust to a new social life and work stage. In addition to inner fear and anxiety about the future, they must also consider how to choose a future career path, how to develop the future prospects of the chosen industry, and how to apply for the position of their choice, etc. These are the issues that graduates must confront and consider, with many in the process of deciding and deliberating. Inevitably, graduates will experience anxiety, worry, indecision, and depression during the process of deciding and pondering, which will negatively impact their mental health. Second, many graduates will complete internships prior to employment. During this process, many graduates will perceive that the actual employment environment and job content are vastly different from their own expectations, resulting in a significant psychological gap that will create pessimism, negativity, and irritability regarding employment and future development, and negatively impact their psychological health. Again, college students are easily influenced by negative ideas prevalent in society and on the Internet, such as money worship and hedonism in the workplace, which results in unemployment and mental health issues. In addition, some college students will decide to start their own business if they lose certain employment opportunities or if they believe the employment unit is not optimal. However, because college students lack social and entrepreneurial experience, they are under a great deal of stress as a result. Employment is a problem that every graduate must face, and it is also the segment most likely to cause mental health issues, requiring educators’ focused attention.Academic stress may result in mental health problems. In addition to selecting a career path, college grads must also decide whether or not to pursue further education. Since graduates are nearing the end of their academic careers, they face significant academic pressure that may lead to mental health issues. Additionally, they must complete their graduation project and defend their thesis. In the first place, graduates must complete academic requirements such as their graduation project and thesis. Many college students pay insufficient attention to their studies, and when they are confronted with a thesis at graduation, they have no idea where to begin. During the thesis writing process, people become anxious, unhappy, and confused, resulting in a great deal of stress and subsequent negative emotions and difficulties. Some students may be expelled from college if they are unable to earn the required number of credits or if they encounter genuine obstacles such as make-up exams and retakes in certain subjects before graduation. After graduating from university, many students choose to continue their education by enrolling in graduate school or studying abroad. Many students will experience confusion, pessimism, lack of confidence, depression, and other negative emotions, as well as doubts about their own decisions, which, if not alleviated in a timely manner, will be detrimental to their mental health [4–7].Graduates are receiving training in mental health; however, it is insufficient to rely solely on professional counselors, as there are many graduates and fewer professional counselors, and many graduates are unwilling to confide their psychological problems to counselors. Therefore, it is necessary to use technical means to identify the mental health issues of students and to educate, guide, and treat them. In this context, the influence of mental disorders education research at universities has grown significantly. In data mining, algorithms are used to discover new information in large amounts of data. These algorithms can intelligently and efficiently analyze and process large amounts of data, and have become increasingly popular in the fields of intelligence retrieval, data analysis, and pattern recognition in recent years. Numerous researchers have shown a great deal of interest in the application of data mining techniques to the study of psychological issues raised by college students and to crisis early warning.


## 2. Related Work

### 2.1. Research on Heart Health

Yu Jiayuan [1, 2] investigated the use of rough sets integrating neural networks in the field of psychological assessment, applied rough sets to relevant data analysis, proposed a genetic algorithm-based fuzzy comprehensive evaluation technique, and conducted a useful analyses of the Likert scale’s psychological measuring data; Yan Jie [3] applied the decision tree mining method to the study of college students’ mental health data, and with the assistance of Clem, constructed a decision tree mining model using the C5.0 algorithm and the C5.0 algorithm for decision tree mining. The solution speed of decision tree is fast, and the classification accuracy is no less than the traditional BP neural network. The decision tree mining model was using C5.0 algorithm with the help of Clem entine12.0 platform to study university students’ mental health; Gao et al. [8] used Hazy set theory to design the core set of factors and applied HMM model to predict college students’ psychological crisis. In their study, Li et al. [9] employed the k-means cluster analysis method to examine students’ performance. He [10] investigated the possibility of incorporating data mining into the investigation of the psychological difficulties of college students and employed the tree algorithm C4.5 was used to examine the data on psychological disorders among college students; Li [4] investigated and predicted the factors influencing college students’ subhealth by the construction of a binary logistic incremental regression model and also a decision tree model; Huang [5] investigated and predicted the factors influencing college students’ subhealth by establishing a binary logistic step the results of prior investigations guided the development and implementation of a college student the CART decision tree is used to create a psychological data mining model, the pattern recognition network (PRN) algorithm, and the algorithm for artificial neural networks (BP) [6]. For the reasons that classification techniques for mental data mining or connection analysis are used, these studies have been able to produce specific research results in their respective disciplines. The data from mental health checks are exceedingly complex, on the other hand, results in specific limitations in performance metrics such as classification accuracy and recall, as well as poor stability while processing diverse data sets. Following the principle of group optimization, we choose decision trees as the fundamental classifier, and we use the integrated learning algorithm Adaboost to develop a powerful classifier that we then use to data mining for college student mental health. Essentially, given a set of psychological training samples, different training sets are obtained by altering the distribution probability of each sample, and each training set is trained to obtain a basic classifier, which is then combined with other basic classifiers according to different weights in order to produce a strong classifier. In addition to avoiding overfitting problems that can arise with other methods, this method steadily lowers the upper bound of the training error rate as the number of iterations grows [7], the class label of even the classifier is massively changed as a result of this enhancement.


### 2.2. A Study on the Classification of Imbalanced Data

Despite the fact that data imbalance is common in tasks such as fraud detection [11] and medical diagnosis [12], Thabtah et al. [13] conducted an experimental investigation into the effect of varying category imbalance rates on classifier accuracy using a Bayesian approach. The bulk of the time, when training a typical classifier with category imbalance data, the classifier is biased towards the majority of the categories.Research on data imbalance classification problems can be broadly divided into three groups, namely, data-level techniques, algorithm-level approaches, and cost-sensitive learning approaches. Data-level approaches are the most common. Undersampling, oversampling, and integrated sampling are all examples of data-level approaches, which are also known as resampling methods. In terms of algorithm-level strategies, Lee et al. [14] suggested fuzzy support vector machines are used to construct an overlap-sensitive margin (OSM) classifier and k-nearest neighbor (KNN) to class imbalance and classes overlap issues. Improving the classification performance of class imbalance data sets using an integration approach is also a popular solution. By combining the advantages of multiple classifiers, integration can produce better performance than using a single classifier. Chawla et al. [15] invented the SMOTEBoost, include SMOTE (synthetic minority oversampling technique) and adaptive enhancement (AdaBoost). Liu et al. [16] proposed easy-ensemble and balance-cascade. Cost-sensitive learning makes use of cost misclassification data and recognizes higher probability to identify the more profitable categories [14].


### 2.3. Integrated Learning

Integration learning compensates for the lack of robustness of a single model subject to large perturbations from sensitive samples by multiple weakly supervised models are being combined in order to produce a more complete strongly supervised model. Integrated learning is divided into two categories: bagging and boosting [17]. Where bagging is represented by the algorithm Random forest (RF) and boosting is characterized by adaptive weighting and represented by the algorithm Adaboost.RF uses Bootstrap sampling to ensure that the training set of each decision tree is different and random, making the RF model less likely to fall into overfitting and has better noise immunity and a more stable prediction capability than a single model [15]. Eventually, the prediction results of all decision trees are averaged as the output of the model, but because the training set is usually unbalanced and small training errors are usually required for certain sample data with large contributions, certain decision trees with large contributions to the integrated model cannot play a greater role. Adaboost adaptively updates the weights of the training samples according to the performance of the weak learner error rate and finally integrates them through an ensemble strategy [16] to improve the accuracy of the model. Unlike RF, Adaboost has the same training set each round and is susceptible to perturbation by sensitive samples.


## 2.1. Research on Heart Health

Yu Jiayuan [1, 2] investigated the use of rough sets integrating neural networks in the field of psychological assessment, applied rough sets to relevant data analysis, proposed a genetic algorithm-based fuzzy comprehensive evaluation technique, and conducted a useful analyses of the Likert scale’s psychological measuring data; Yan Jie [3] applied the decision tree mining method to the study of college students’ mental health data, and with the assistance of Clem, constructed a decision tree mining model using the C5.0 algorithm and the C5.0 algorithm for decision tree mining. The solution speed of decision tree is fast, and the classification accuracy is no less than the traditional BP neural network. The decision tree mining model was using C5.0 algorithm with the help of Clem entine12.0 platform to study university students’ mental health; Gao et al. [8] used Hazy set theory to design the core set of factors and applied HMM model to predict college students’ psychological crisis. In their study, Li et al. [9] employed the k-means cluster analysis method to examine students’ performance. He [10] investigated the possibility of incorporating data mining into the investigation of the psychological difficulties of college students and employed the tree algorithm C4.5 was used to examine the data on psychological disorders among college students; Li [4] investigated and predicted the factors influencing college students’ subhealth by the construction of a binary logistic incremental regression model and also a decision tree model; Huang [5] investigated and predicted the factors influencing college students’ subhealth by establishing a binary logistic step the results of prior investigations guided the development and implementation of a college student the CART decision tree is used to create a psychological data mining model, the pattern recognition network (PRN) algorithm, and the algorithm for artificial neural networks (BP) [6]. For the reasons that classification techniques for mental data mining or connection analysis are used, these studies have been able to produce specific research results in their respective disciplines. The data from mental health checks are exceedingly complex, on the other hand, results in specific limitations in performance metrics such as classification accuracy and recall, as well as poor stability while processing diverse data sets. Following the principle of group optimization, we choose decision trees as the fundamental classifier, and we use the integrated learning algorithm Adaboost to develop a powerful classifier that we then use to data mining for college student mental health. Essentially, given a set of psychological training samples, different training sets are obtained by altering the distribution probability of each sample, and each training set is trained to obtain a basic classifier, which is then combined with other basic classifiers according to different weights in order to produce a strong classifier. In addition to avoiding overfitting problems that can arise with other methods, this method steadily lowers the upper bound of the training error rate as the number of iterations grows [7], the class label of even the classifier is massively changed as a result of this enhancement.


## 2.2. A Study on the Classification of Imbalanced Data

Despite the fact that data imbalance is common in tasks such as fraud detection [11] and medical diagnosis [12], Thabtah et al. [13] conducted an experimental investigation into the effect of varying category imbalance rates on classifier accuracy using a Bayesian approach. The bulk of the time, when training a typical classifier with category imbalance data, the classifier is biased towards the majority of the categories.Research on data imbalance classification problems can be broadly divided into three groups, namely, data-level techniques, algorithm-level approaches, and cost-sensitive learning approaches. Data-level approaches are the most common. Undersampling, oversampling, and integrated sampling are all examples of data-level approaches, which are also known as resampling methods. In terms of algorithm-level strategies, Lee et al. [14] suggested fuzzy support vector machines are used to construct an overlap-sensitive margin (OSM) classifier and k-nearest neighbor (KNN) to class imbalance and classes overlap issues. Improving the classification performance of class imbalance data sets using an integration approach is also a popular solution. By combining the advantages of multiple classifiers, integration can produce better performance than using a single classifier. Chawla et al. [15] invented the SMOTEBoost, include SMOTE (synthetic minority oversampling technique) and adaptive enhancement (AdaBoost). Liu et al. [16] proposed easy-ensemble and balance-cascade. Cost-sensitive learning makes use of cost misclassification data and recognizes higher probability to identify the more profitable categories [14].


## 2.3. Integrated Learning

Integration learning compensates for the lack of robustness of a single model subject to large perturbations from sensitive samples by multiple weakly supervised models are being combined in order to produce a more complete strongly supervised model. Integrated learning is divided into two categories: bagging and boosting [17]. Where bagging is represented by the algorithm Random forest (RF) and boosting is characterized by adaptive weighting and represented by the algorithm Adaboost.RF uses Bootstrap sampling to ensure that the training set of each decision tree is different and random, making the RF model less likely to fall into overfitting and has better noise immunity and a more stable prediction capability than a single model [15]. Eventually, the prediction results of all decision trees are averaged as the output of the model, but because the training set is usually unbalanced and small training errors are usually required for certain sample data with large contributions, certain decision trees with large contributions to the integrated model cannot play a greater role. Adaboost adaptively updates the weights of the training samples according to the performance of the weak learner error rate and finally integrates them through an ensemble strategy [16] to improve the accuracy of the model. Unlike RF, Adaboost has the same training set each round and is susceptible to perturbation by sensitive samples.


## 3. Method

### 3.1. Mental Health Prediction Model

To achieve these objectives, a psychological health forecasting model is developed. It reads in the instructional sample data, cleans and normalizes it, and then assigns initial weights to all samples; it then uses the C4.5 algorithm to train the sample set with the anywayD composed of all test weights as parameters to obtain a set of basic classifiers; it then uses the Adaboost algorithm to compute the graded error rate of basic classifiers and obtains the classifier weights as parameters once; and it then uses the Adaboost algorithm to obtain the classifier weights as parameters. After multiple training rounds, a significant classifier was obtained, which was then used to process mental health data, identify mental health variables, and provide accurate estimates. A model for predicting psychological well-being is depicted in Figure 1.Figure 1
Mental health prediction model.After data preprocessing, different sample sets are extracted and distributed with different weights and then entered into the C4.5 training classifier to obtain different classifications, after which the results of the classifications are summed up based on the various weights to obtain a final effective classifier, and the samples to be tested are input into the final strong classifier to obtain our predicted samples, as shown in Figure1.


### 3.2. Key Techniques

#### 3.2.1. Basic Classifier Generation Algorithm

This research uses the decision tree algorithm C4.5 as the fundamental classifier in order to generate classification algorithms. This model, also known as the rule-based inference model, establishes classification rules by learning from training samples and then categorizes new samples based on the classification rules established by the training samples. Compared to other classification models, it performs significantly better in non-numerical data processing and has the potential to reduce a substantial amount of data preprocessing effort. In this study, we construct decision trees using the C4.5 decision tree algorithm, the most popular decision tree technique. C4.5 is an enhanced decision tree method proposed byJ Ross Quinlan on the basis of ID3, which is based on the theory of information and classifies data according to information entropy and information gain rate. C4.5 considers the rate of information gain as a criterion for selecting branching attributes, thereby overcoming the disadvantage of selecting characteristics with greater values based on information gain. Furthermore, C4.5 is able to effectively deal with incomplete and nondiscrete data.Assuming thatS = {X1, X2, ..., Xn} represents the training sample set containing n student psychological test data samples, and attributeSet represents the attribute value data set of S, the steps of algorithm C4.5 Decision-Tree for constructing Decision-Tree are(1)
Create the Decision-Tree root node Root.(2)
In case all of the samples in S are members of the same category C, return Root as a leaf node and mark it as a member of the category C.(3)
If the attributeSet is empty or the number of remaining samples in S is less than the set threshold, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node; otherwise, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node.(4)
Compute the gain ratio of the Gainratio(A) for each A ∈ attributeSet.(5)
The attribute A with the largest value of Gainratio (A) in the attributeSet is taken as the test attribute (best split attribute) Atest of Root.(6)
If the test attribute Atest is continuous, find the splitting threshold of the attribute.(7)
For each leaf node generated by a node Root based on Atest, check whether the sample subset S′ associated with this leaf node is empty before splitting the leaf node to generate a new leaf node and designating it as the class with the greatest number of classes in the samples contained within this node. If this is the case, the decision tree construction method C4.5 Decision-Tree (S′, S′, attributeSet) is conducted on this leaf node, and the splitting of the tree is carried out again.(8)
Calculate the classification error of each node and prune the Decision-Tree.


#### 3.2.2. Building a Powerful Classifier by Adaboost

The Adaboost algorithm [17] is a modified Boosting algorithm that adapts the errors of weak classifiers (basic classifiers) obtained from weak learning to obtain an effective classifier with high degree of accuracy in classification. In this paper, the process of creating an effective classifier using Adaboost is as follows: a training sample is obtained after preprocessing the mental health test data, a series of basic classifiers are generated by repeatedly calling the C4.5 algorithm, and each basic classifier is assigned a certain weight according to its classification correctness, and then these classifiers are combined to obtain a strong classifier. When detecting new samples to be detected, the samples to be detected are given to each basic classifier in parallel for classification, the weights of the classifiers with the same classification result are added together, and the result with the highest weight is finally taken as the final output of the strong classifier. The steps for constructing a classifier using this algorithm areIn the first step, input a sample set containingN training samples of mental health data.(1)D=x1,y1,…,xi,yi,…,xN,yN,xI∈X,yI∈Y.X is sample set, Y is the sample category, Y = {−1, +1}, and each sample xi contains K-dimensional features {vi (xi), 1 ≤ j ≤ K}.In the second step, the weight distribution of the sample set is initialized.(2)D1=w1x1,w1x1=1N,i=1,2,…,N.In the third step, for anyt ∈｛1, 2, ..., T}, T is the number of classifiers, a loop is executed.(1)
Using the samples with weight distributionDt for learning, train a basic classifier hj for each vix:(3)hj=1,pivix<pjθj,−1,pivix≥pjθj,whereθi is the threshold value, pj is the bias value, and pj ∈ {−1, 1}. Calculate the weighted.Calculate the weighted error rate.(4)εj=∑i=1nwtxthjxi≠yi.Thehj corresponding to the minimum value of the error rate εj, and εt is used as the basic classifier ht for this cycle.(2)
Calculate the weighting parameterαt of ht:(5)αt=12ln1−εtεt.(3)
Update the weight distribution using the weightαt.(6)Dt+1=wt+1xi,wt+1xi=wtxie−αtyihtxiZt.Zt as the normalization factor Zt=∑wtxie−αtyihtxi.In the fourth step, the final strong classifier H(x) is constructed using theT optimal basic classifiers obtained from T rounds of training.(7)Hx=sing∑t=1athtx.


### 3.3. Model Evaluation Methods

For measuring a model’s performance, suitable evaluation metrics are required. Commonly employed classification model evaluation metrics may not be a good indicator of the performance of classification models for imbalanced data. Commonly employed evaluation metrics for unbalanced data classification models include specificity, G-mean, and CK [2]. Specificity measures the accuracy of classification for a small number of samples; G-mean and CK combine the accuracy of large and small categories to measure overall performance. As shown in Table 1, a confusion matrix of classification results can be formed for the dichotomous classification problem based on the combination of true and predicted categories.Table 1
Confusion matrix of binary classification results.
RealPredictionPositiveNegativeTrueTPTNFalseFPFNBased on the confusion matrix, the accuracy, AUC value, specificity, G-mean and CK are used to evaluate the model in this paper.(i)
The accuracy rate is a measure of the percentage of correctly classified samples, i.e., the proportion of all correctly classified samples to the total number of samples, as shown in(8)Accuracy=TP+TNTP+TN+FP+FN.(ii)
AUC value is calculated as the area of the ROC curve, and the ROC curve is a fit to the results of a model under different thresholds. Generally, the larger the AUC value, the better the prediction of the model.(iii)
The specificity is used to evaluate the correct rate of classification for a few classes of samples, as shown in(9)Specificity=TNTN+FP.(iv)
The geometric mean of both the accuracy in classification achieved by the majority and the accuracy in classification achieved by the minority is denoted by G-mean, with the goal of maximizing both classes while preserving a healthy balance between both the majority class classifier and the minorities class classification accuracy as illustrated in(10)G−mean=TP×TNTN+FPTP+FN.(v)
CK, the Kappa Coefficient, can be used to evaluate the classification ability of the model, and the value range is [−1, 1], but usually [0, 1]. The larger the CK value is, the higher the consistency between the prediction result and the actual result, and the better the performance of the classification model, as shown in(11)CK=Accuracy−CKc1−CKc.where accuracy is the accuracy rate;CKc is shown in(12)CKc=TP+FNTP+FP+FP+TNFN+TNTP+FN+TN+FP2.


## 3.1. Mental Health Prediction Model

To achieve these objectives, a psychological health forecasting model is developed. It reads in the instructional sample data, cleans and normalizes it, and then assigns initial weights to all samples; it then uses the C4.5 algorithm to train the sample set with the anywayD composed of all test weights as parameters to obtain a set of basic classifiers; it then uses the Adaboost algorithm to compute the graded error rate of basic classifiers and obtains the classifier weights as parameters once; and it then uses the Adaboost algorithm to obtain the classifier weights as parameters. After multiple training rounds, a significant classifier was obtained, which was then used to process mental health data, identify mental health variables, and provide accurate estimates. A model for predicting psychological well-being is depicted in Figure 1.Figure 1
Mental health prediction model.After data preprocessing, different sample sets are extracted and distributed with different weights and then entered into the C4.5 training classifier to obtain different classifications, after which the results of the classifications are summed up based on the various weights to obtain a final effective classifier, and the samples to be tested are input into the final strong classifier to obtain our predicted samples, as shown in Figure1.


## 3.2. Key Techniques

### 3.2.1. Basic Classifier Generation Algorithm

This research uses the decision tree algorithm C4.5 as the fundamental classifier in order to generate classification algorithms. This model, also known as the rule-based inference model, establishes classification rules by learning from training samples and then categorizes new samples based on the classification rules established by the training samples. Compared to other classification models, it performs significantly better in non-numerical data processing and has the potential to reduce a substantial amount of data preprocessing effort. In this study, we construct decision trees using the C4.5 decision tree algorithm, the most popular decision tree technique. C4.5 is an enhanced decision tree method proposed byJ Ross Quinlan on the basis of ID3, which is based on the theory of information and classifies data according to information entropy and information gain rate. C4.5 considers the rate of information gain as a criterion for selecting branching attributes, thereby overcoming the disadvantage of selecting characteristics with greater values based on information gain. Furthermore, C4.5 is able to effectively deal with incomplete and nondiscrete data.Assuming thatS = {X1, X2, ..., Xn} represents the training sample set containing n student psychological test data samples, and attributeSet represents the attribute value data set of S, the steps of algorithm C4.5 Decision-Tree for constructing Decision-Tree are(1)
Create the Decision-Tree root node Root.(2)
In case all of the samples in S are members of the same category C, return Root as a leaf node and mark it as a member of the category C.(3)
If the attributeSet is empty or the number of remaining samples in S is less than the set threshold, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node; otherwise, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node.(4)
Compute the gain ratio of the Gainratio(A) for each A ∈ attributeSet.(5)
The attribute A with the largest value of Gainratio (A) in the attributeSet is taken as the test attribute (best split attribute) Atest of Root.(6)
If the test attribute Atest is continuous, find the splitting threshold of the attribute.(7)
For each leaf node generated by a node Root based on Atest, check whether the sample subset S′ associated with this leaf node is empty before splitting the leaf node to generate a new leaf node and designating it as the class with the greatest number of classes in the samples contained within this node. If this is the case, the decision tree construction method C4.5 Decision-Tree (S′, S′, attributeSet) is conducted on this leaf node, and the splitting of the tree is carried out again.(8)
Calculate the classification error of each node and prune the Decision-Tree.


### 3.2.2. Building a Powerful Classifier by Adaboost

The Adaboost algorithm [17] is a modified Boosting algorithm that adapts the errors of weak classifiers (basic classifiers) obtained from weak learning to obtain an effective classifier with high degree of accuracy in classification. In this paper, the process of creating an effective classifier using Adaboost is as follows: a training sample is obtained after preprocessing the mental health test data, a series of basic classifiers are generated by repeatedly calling the C4.5 algorithm, and each basic classifier is assigned a certain weight according to its classification correctness, and then these classifiers are combined to obtain a strong classifier. When detecting new samples to be detected, the samples to be detected are given to each basic classifier in parallel for classification, the weights of the classifiers with the same classification result are added together, and the result with the highest weight is finally taken as the final output of the strong classifier. The steps for constructing a classifier using this algorithm areIn the first step, input a sample set containingN training samples of mental health data.(1)D=x1,y1,…,xi,yi,…,xN,yN,xI∈X,yI∈Y.X is sample set, Y is the sample category, Y = {−1, +1}, and each sample xi contains K-dimensional features {vi (xi), 1 ≤ j ≤ K}.In the second step, the weight distribution of the sample set is initialized.(2)D1=w1x1,w1x1=1N,i=1,2,…,N.In the third step, for anyt ∈｛1, 2, ..., T}, T is the number of classifiers, a loop is executed.(1)
Using the samples with weight distributionDt for learning, train a basic classifier hj for each vix:(3)hj=1,pivix<pjθj,−1,pivix≥pjθj,whereθi is the threshold value, pj is the bias value, and pj ∈ {−1, 1}. Calculate the weighted.Calculate the weighted error rate.(4)εj=∑i=1nwtxthjxi≠yi.Thehj corresponding to the minimum value of the error rate εj, and εt is used as the basic classifier ht for this cycle.(2)
Calculate the weighting parameterαt of ht:(5)αt=12ln1−εtεt.(3)
Update the weight distribution using the weightαt.(6)Dt+1=wt+1xi,wt+1xi=wtxie−αtyihtxiZt.Zt as the normalization factor Zt=∑wtxie−αtyihtxi.In the fourth step, the final strong classifier H(x) is constructed using theT optimal basic classifiers obtained from T rounds of training.(7)Hx=sing∑t=1athtx.


## 3.2.1. Basic Classifier Generation Algorithm

This research uses the decision tree algorithm C4.5 as the fundamental classifier in order to generate classification algorithms. This model, also known as the rule-based inference model, establishes classification rules by learning from training samples and then categorizes new samples based on the classification rules established by the training samples. Compared to other classification models, it performs significantly better in non-numerical data processing and has the potential to reduce a substantial amount of data preprocessing effort. In this study, we construct decision trees using the C4.5 decision tree algorithm, the most popular decision tree technique. C4.5 is an enhanced decision tree method proposed byJ Ross Quinlan on the basis of ID3, which is based on the theory of information and classifies data according to information entropy and information gain rate. C4.5 considers the rate of information gain as a criterion for selecting branching attributes, thereby overcoming the disadvantage of selecting characteristics with greater values based on information gain. Furthermore, C4.5 is able to effectively deal with incomplete and nondiscrete data.Assuming thatS = {X1, X2, ..., Xn} represents the training sample set containing n student psychological test data samples, and attributeSet represents the attribute value data set of S, the steps of algorithm C4.5 Decision-Tree for constructing Decision-Tree are(1)
Create the Decision-Tree root node Root.(2)
In case all of the samples in S are members of the same category C, return Root as a leaf node and mark it as a member of the category C.(3)
If the attributeSet is empty or the number of remaining samples in S is less than the set threshold, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node; otherwise, return Root as a leaf node and mark Root as the class with the greatest number of categories among the samples contained in the node.(4)
Compute the gain ratio of the Gainratio(A) for each A ∈ attributeSet.(5)
The attribute A with the largest value of Gainratio (A) in the attributeSet is taken as the test attribute (best split attribute) Atest of Root.(6)
If the test attribute Atest is continuous, find the splitting threshold of the attribute.(7)
For each leaf node generated by a node Root based on Atest, check whether the sample subset S′ associated with this leaf node is empty before splitting the leaf node to generate a new leaf node and designating it as the class with the greatest number of classes in the samples contained within this node. If this is the case, the decision tree construction method C4.5 Decision-Tree (S′, S′, attributeSet) is conducted on this leaf node, and the splitting of the tree is carried out again.(8)
Calculate the classification error of each node and prune the Decision-Tree.


## 3.2.2. Building a Powerful Classifier by Adaboost

The Adaboost algorithm [17] is a modified Boosting algorithm that adapts the errors of weak classifiers (basic classifiers) obtained from weak learning to obtain an effective classifier with high degree of accuracy in classification. In this paper, the process of creating an effective classifier using Adaboost is as follows: a training sample is obtained after preprocessing the mental health test data, a series of basic classifiers are generated by repeatedly calling the C4.5 algorithm, and each basic classifier is assigned a certain weight according to its classification correctness, and then these classifiers are combined to obtain a strong classifier. When detecting new samples to be detected, the samples to be detected are given to each basic classifier in parallel for classification, the weights of the classifiers with the same classification result are added together, and the result with the highest weight is finally taken as the final output of the strong classifier. The steps for constructing a classifier using this algorithm areIn the first step, input a sample set containingN training samples of mental health data.(1)D=x1,y1,…,xi,yi,…,xN,yN,xI∈X,yI∈Y.X is sample set, Y is the sample category, Y = {−1, +1}, and each sample xi contains K-dimensional features {vi (xi), 1 ≤ j ≤ K}.In the second step, the weight distribution of the sample set is initialized.(2)D1=w1x1,w1x1=1N,i=1,2,…,N.In the third step, for anyt ∈｛1, 2, ..., T}, T is the number of classifiers, a loop is executed.(1)
Using the samples with weight distributionDt for learning, train a basic classifier hj for each vix:(3)hj=1,pivix<pjθj,−1,pivix≥pjθj,whereθi is the threshold value, pj is the bias value, and pj ∈ {−1, 1}. Calculate the weighted.Calculate the weighted error rate.(4)εj=∑i=1nwtxthjxi≠yi.Thehj corresponding to the minimum value of the error rate εj, and εt is used as the basic classifier ht for this cycle.(2)
Calculate the weighting parameterαt of ht:(5)αt=12ln1−εtεt.(3)
Update the weight distribution using the weightαt.(6)Dt+1=wt+1xi,wt+1xi=wtxie−αtyihtxiZt.Zt as the normalization factor Zt=∑wtxie−αtyihtxi.In the fourth step, the final strong classifier H(x) is constructed using theT optimal basic classifiers obtained from T rounds of training.(7)Hx=sing∑t=1athtx.


## 3.3. Model Evaluation Methods

For measuring a model’s performance, suitable evaluation metrics are required. Commonly employed classification model evaluation metrics may not be a good indicator of the performance of classification models for imbalanced data. Commonly employed evaluation metrics for unbalanced data classification models include specificity, G-mean, and CK [2]. Specificity measures the accuracy of classification for a small number of samples; G-mean and CK combine the accuracy of large and small categories to measure overall performance. As shown in Table 1, a confusion matrix of classification results can be formed for the dichotomous classification problem based on the combination of true and predicted categories.Table 1
Confusion matrix of binary classification results.
RealPredictionPositiveNegativeTrueTPTNFalseFPFNBased on the confusion matrix, the accuracy, AUC value, specificity, G-mean and CK are used to evaluate the model in this paper.(i)
The accuracy rate is a measure of the percentage of correctly classified samples, i.e., the proportion of all correctly classified samples to the total number of samples, as shown in(8)Accuracy=TP+TNTP+TN+FP+FN.(ii)
AUC value is calculated as the area of the ROC curve, and the ROC curve is a fit to the results of a model under different thresholds. Generally, the larger the AUC value, the better the prediction of the model.(iii)
The specificity is used to evaluate the correct rate of classification for a few classes of samples, as shown in(9)Specificity=TNTN+FP.(iv)
The geometric mean of both the accuracy in classification achieved by the majority and the accuracy in classification achieved by the minority is denoted by G-mean, with the goal of maximizing both classes while preserving a healthy balance between both the majority class classifier and the minorities class classification accuracy as illustrated in(10)G−mean=TP×TNTN+FPTP+FN.(v)
CK, the Kappa Coefficient, can be used to evaluate the classification ability of the model, and the value range is [−1, 1], but usually [0, 1]. The larger the CK value is, the higher the consistency between the prediction result and the actual result, and the better the performance of the classification model, as shown in(11)CK=Accuracy−CKc1−CKc.where accuracy is the accuracy rate;CKc is shown in(12)CKc=TP+FNTP+FP+FP+TNFN+TNTP+FN+TN+FP2.


## 4. Experimental Results and Analysis

The data used for the experiment in this paper were collected from the mental health test and personality test data of students in the class of 2022 at a university. These tests were administered online with the cooperation of the university’s counseling center, and 2,780 valid questionnaires were collected. The mental health examination scale utilized the Symptom Self-Rating Scale SCL90, a commonly used outpatient examination scale for mental disorders and psychological disorders. The SCL90 scale has 90 entries, 10 factors were considered, including somatization, obsessive-compulsion symptoms, prosocial behavior, depression, anxiety, anger; terror; paranoia; psychoticism; and others, with each entry having 5 subscales. There are five options for every item: 1 (none), 2 (very mild), 3 (moderate), 4 (severe), and 5 (severe). The Eysenck Personality Questionnaire (EPQ), which consists of four scales: the Extraversion Scale (E), the Emotional Disposition Scale (N), the Psychological Quality Scale (P), and the Validity Scale, was used to administer the personality test (L). The first three scales, which are independent of one another, reflect the three distinct dimensions of human personality, whereas the L is a validity scale that reflects the hypothetical personality traits and the level of social simplicity and naiveté. In this study, the Chinese version of the Eysenck Personality Questionnaire Short Form Scale was utilized (EPQ-RSC).Due to the fact that a small number of test scales may contain missing items or irregular filling, data cleansing is required prior to processing in order to verify data consistency, perform data normalization, eliminate invalid values, account for missing values, etc. Since the possible response options for the scale entries are discrete values, the most frequent value of that item is counted to fill in the missing values. In order to facilitate the algorithm for data processing, coded representations of all questionnaire entries’ values were abstracted. The database management system SQL Server 2012 was used to store data, and the database tables “SCLTable” and “EPQTable” were created to store the symptom self-assessment scale and Eysenck personality questionnaire data, respectively. The relationship between the two tables was established by the “StudentID” attribute. The experiment was conducted on a Dell Inspiron 3650-D1838 using a Python-programmed algorithm. A training set and a test set were created from the test samples. There were 1,800 samples for training and 980 for testing. In order to ensure the generality of the algorithm, the hyperparameter settings in this paper are consistent with those in Reference 4.The impact of erasing these records on other variables was examined through additional analysis. According to the results, the effect of deleting these records on the distribution of other variables was insignificant, so it was deemed acceptable to delete this portion of the data. As shown in Figure2, there was no significant difference between the distribution of the variable age before and after the deletion of the data. In addition, the values of the age group were compared by calculating the weighted average instead of the mean and the standard deviation, and it was found that the differences were minimal.Figure 2
Data distribution map. (a) Before deleting data, (b) after deleting data.
(a)(b)The base classifier is GBDT, and the Gradient Boosting Classifier algorithm in “sklearn. Ensemble” is called, and some relevant parameters are obtained by the grid search algorithm, and the others are default values, as shown in Table2. For the determination of the number of base classifiers T, the variation of the evaluation index of different number of base classifiers is experimentally explored, as shown in Figure 2. It is known that the model shows better results on each evaluation index when T is 9, so the hyper parameter T is set to 9.Table 2
Some parameters of GBDT.
ParameterValueLearning_rate0.1Max_depth4Min_sample_split4N_estimators100For the determination of the number of base classifiersT, the variation of evaluation indexes with different numbers of base classifiers is experimentally explored, as shown in Figure 3. It can be seen that the model shows better results on each evaluation index when T is 9, so the hyper parameter T is set to 9.Figure 3
Evaluation indicators for various number-based classifiers.
(a)(b)(c)(d)(e)After determining the data division and parameters, the performance of the model is evaluated. Numerous machine learning algorithms have been applied to medical prediction and have demonstrated good performance; these algorithms can be broadly categorized as either single models or integrated models. Single models consist primarily of Decision Tree (DT), Logistic Regression (LR), and K-Nearest Neighbor (KNN), among others. Also included is the more popular Artificial Neural Network (ANN). The majority of the integration models are Random Forest (RF), AdaBoost, and Gradient Boosted Decision Tree (GBDT). The primary methods for processing unbalanced data are oversampling, downsampling, and integrated sampling. The SMOTETomek method of integrated sampling incorporates oversampling and undersampling and performs reasonably well. The integrated model demonstrates superior classification performance, and SMOTETomek in conjunction with the integrated model can effectively address the data imbalance issue. This article also compares the model to SMOTETomek in conjunction with the integrated model to address data imbalance. Table3 compares the effectiveness of various algorithms utilizing the SEER Gastric Cancer Data set.Table 3
Using the SEER gastric cancer data set, we compared the performance of various algorithms.
TypeAlgorithmsAccuracyAUCSpecificityG-meanCKSingle modelDT [18]0.7800.6670.4720.4060.329LR [19]0.8250.8350.2740.2650.310KNN [20]0.8230.8400.3520.3330.352ANN [21]0.8360.8520.3800.3620.400Integrated modelRF [22]0.8440.8770.4600.4340.457Boosting [17]0.8430.8760.4630.4360.457GBDT [23]0.8480.8800.4800.4520.476Data imbalance processing + integrated modelSMOTETomek + RF0.8270.8670.6660.5780.502SMOTETomek + boosting0.8050.8600.7080.5870.474SMOTETomek + GBDT0.8150.8680.7270.6090.498BalancedRandomForest0.7590.8510.8190.6080.432Easy-Ensemble0.7870.8770.8190.6380.478Ours0.8080.8830.8350.6500.528


## 5. Conclusion

Modern college students are subjected to unprecedented levels of stress from their studies, jobs, and interpersonal relationships, and the resulting psychological issues are becoming increasingly prevalent, with occasional violent acts occurring as a result. In this study, we provide a method for predicting the mental health of graduates by employing the decision tree algorithm C4.5 as the primary classifier and the Adaboost classifier developed by the integrated learning algorithm as the secondary classifier. The experimental results of the algorithm demonstrate that the accuracy and recall of the classification indices of the integrated learning classifier are significantly improved as a result of employing this strategy. This algorithm may assist mental health counseling teachers, student management, and counselors in understanding students’ psychological development, the main symptoms and personality traits of mental health problems, and focusing on students who may be suffering from mental health problems and providing them with more care, guidance, and psychological treatment to prevent the problems from occurring. In the future, we will introduce deep learning models to predict mental health.



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*Source: 5761815-2022-06-25.xml*