Dimensional and internal structure of the Zung' self-rating depression scale in urban recyclable waste pickers

The dimensional and internal structure of the instruments can vary significantly according to the population. The objective of the study was to corroborate the dimensional and internal structure of the Zung's brief scale in people dedicated to the recycling of urban waste. A methodological study was designed. A sample of 206 adults, between 18 and 70 years (M=37.7, SD=12.5); 147 men and 59 women. Participants completed the ten items of the scale. The dimensional structure was tested by confirmatory factor analysis and calculated goodness-of-fit indexes: chi-square, RMSEA (Root Mean Square Error of Approximation), CFI (Comparative Fit Index), TLI (Tucker-Lewis index) and SMSR (Standardized Mean Square Residual). The internal structure was tested with Cronbach's alpha and McDonald's omega. The two-dimensional structure was tested: the first factor (depressed mood-anxiety) and the second (anhedonia-cognition). The fit indices were chi square=126.83, degrees of freedom=34, p=0.001; RMSEA=0.115 (IC90% 0.094-0.137), CFI=0.851, TLI=0.802, and SRMS=0.075. The first dimension showed both Cronbach's alpha and McDonald's omega of 0.80; and the second, alpha of 0.71 and omega of 0.72. The structure of the Zung scale for depression was not corroborated. A larger sample can give more conclusive information.