A study is conducted to determine whether sunshine affects depression. Eight individuals are given a questionnaire measuring depression immediately following a run of 10 consecutive days when the sun shone for over 80% of the daylight hours. The same individuals have their depression measured immediately following 10 consecutive days without any sunshine. The following data are collected: The higher the score, the greater the depression.
Individuals:
Sunshine: 10, 12
No sunshine: 21, 17, 14, 18, 18
Using the Wilcoxon signed ranks test to evaluate the data, the value of T_obt is...