In article by Naeim et al in the June issue of Addictive Disorders Their Treatment, the Results section was written incorrectly. The research findings section, central indices, and dispersion indices, such as mean and standard deviation were used. For inferential analysis, analysis of covariance and significance level of 0.05 were used. To observe the assumptions of the analysis of covariance, the results of Levene’s and Box’s M tests were examined. The mentioned analyzes were performed using SPSS software version 22. To correct this data, the Results section is republished via this erratum.1

RESULTS

In total, there were 40 participants (20 in the experimental group, 20 in the control group). Descriptive findings of this study including statistical indices of mean and standard deviation for all variables under study are presented in Table 1.

TABLE 1 - Mean and Standard Deviation of Research Variables in Experimental and Control Groups In Pre-Test and Posttest Examination Group Control Group Variable Test Mean SD Mean SD Depression Pretest 59.28 3.26 58.84 2.98 Posttest 38.62 8.93 61.50 6.17 Anxiety Pretest 77.15 6.94 76.93 8.61 Posttest 56.78 6.14 77.48 7.95

Table 1 shows the mean and standard deviation of the research variables of experimental and control groups in pre-test and post-test. The results indicate the effectiveness of tDCS treatment in the experimental group compared to the control group. Before analyzing the data related to the hypotheses, they were examined to ensure that the underlying assumptions of covariance analysis were met. For this purpose, the normality of data distribution by Shapiro-Wilk test showed that the distribution of scores in the research variables is normal (P <0.05). Also, Levene’s test was used to test the assumption of homogeneity of variance (for the same variance of the experimental and control groups).

The Box’s M test was used to test the hypothesis of homogeneity of covariances. Also, analysis of variance was used to investigate the assumption of homogeneity of regression line slope. According to the results, the analysis of covariance can be used. In the following, Table 2 shows the results of univariate analysis of covariance for post-test scores in dependent variables.

TABLE 2 - Results of Univariate Analysis of Covariance on Posttest Scores of Depression and Anxiety Variable F P Eta Statistical Power Depression 12.27 0.002 0.391 0.895 Anxiety 11.51 0.003 0.375 0.871

As can be seen in Table 2, the results of univariate analysis of covariance for dependent variables show that after removing the pretest effect on the variables of depression (P <0.002, F = 12.27) and anxiety (P = 0.003, F = 11.51) between the experimental groups. And there is a significant difference in post-test control. Depression and anxiety are 0.391 and 0.375, respectively, indicating a relatively high effect of tDCS treatment on depression and anxiety in methadone users.

REFERENCE 1. Naeim M, Rezaeisharif A, Bagvand SG. Determining the effect of transcranial direct current stimulation on depression and anxiety in methadone consumers: a randomized controlled: erratum. Addict Disorders Their Treatment. 2021;20:141–145. doi: 10.1097/ADT.0000000000000234.