Therefore, one of the major sources of error for the BDI, which contains 21 items with a possible score range from 0 to 63, includes the risk of developing different interpretations of test scores depending on the rater. Bumberry et al. (1978) addressed this issue by calculating a Pearson product-moment correlation coefficient between primary (i.e. structured interview used for over 2 decades) and secondary raters (i.e. board certified psychiatrists with 9 and 4 years of experience). Researchers found that inter-rater reliability between the primary psychiatrist and the two other psychiatrists was .62. Because the reliability coefficient is relatively high, we can assume that the BDI is a reliable test to assess the current depth of depression. Similarly, Lahlou-Laforet et al. (2015), which aimed to validate the French version of the BDI in chronic heart failure (CHF) patients, assessed inter-rater reliability of the BDI through 23 interviews rated by three psychiatrists. Using an Intra-class correlation coefficient, researchers found that inter-rater reliability was .87, suggesting that the BDI is a reliable test to assess depression in CHF
Therefore, one of the major sources of error for the BDI, which contains 21 items with a possible score range from 0 to 63, includes the risk of developing different interpretations of test scores depending on the rater. Bumberry et al. (1978) addressed this issue by calculating a Pearson product-moment correlation coefficient between primary (i.e. structured interview used for over 2 decades) and secondary raters (i.e. board certified psychiatrists with 9 and 4 years of experience). Researchers found that inter-rater reliability between the primary psychiatrist and the two other psychiatrists was .62. Because the reliability coefficient is relatively high, we can assume that the BDI is a reliable test to assess the current depth of depression. Similarly, Lahlou-Laforet et al. (2015), which aimed to validate the French version of the BDI in chronic heart failure (CHF) patients, assessed inter-rater reliability of the BDI through 23 interviews rated by three psychiatrists. Using an Intra-class correlation coefficient, researchers found that inter-rater reliability was .87, suggesting that the BDI is a reliable test to assess depression in CHF