Study conducted to determine whether sunshine affects depression. 8 people are given a survey ...

     Study   conducted to determine whether sunshine affects depression. 8 people are   given a survey immediately following a run of 10 consecutive days when they   were in the sun for over 80% of the daylight hours. The same individuals had   their depression measured immediately following 10 consecutive days without   any sunshine. Following was collected..... the higher the score the greater   the depression. Consider higher depression on days without sun a   success.       Individual 1 2 3 4 5 6 7 8   Sunshine 10 12 14 11 12 10 14   15   No Sun 20 21 17 14 18 8 18 14      a. Conduct null hypothesis   significance test to determine whether lack of sunshine increases   depression.    b. Given design of the study,   are the researchers able to draw casual conclusions? why or why not?