The degree of freedom (df) df = (1 - 1) + (2 - 1) = (15 - 1) + (15 -1) = 14 + 14 = 28

Note. 1 = the number of people in Group 1; 2 = the number of people in Group 2.

The uppercase N means the total number of people in the study, which equals to 30.

(b) level: the standard is = 0.05 (c) The critical value for t is _________________ (a)

Because the observed t value is _________(e)_ (less than, equal to, more than) the critical t-value, the null hypothesis is ___________ (rejected, retained). In other words, there is a _____________ (significant/nonsignificant) finding. In other words, staff checking emails once a day have significantly __________ (higher/lower) productivity than staff checking emails five times a day