What does the variance indicate?
The high variance of South Africa of 3.08 implies that 66% of the scores range between 3,3 and 6,8 (this is computed by taking the square root of the variance and by adding and subtracting this value from the average score to obtain the upper and lower bound), likewise 95% of the scores range between 2,55 and 8,55. Apparently, the average score is only to a very limited degree an assessment of the observed degree of corruption. The low variance of Thailand on the other hand indicates, that 95% of the scores range between 2,54 and 3,98. There seems to be a coherent impression of the degree of corruption in Thailand. Deviating scores can on the one hand be due to diverging perceptions regarding what has to be interpreted as corrupt and to different experiences made with respective countries. It can also be due to objective difficulties in assessing the “right” score. In countries where some institutions still resist corruption while others are openly engaging in illegitimite practices an
