In: Math
A health psychologist conducted an experiment in which participants watched a film that either did or did not include a person being injured because of not wearing a seatbelt. A week later, as part of a seemingly different study, these same participants reported how important they thought it was to wear seatbelts (higher scores = greater importance). The 16 participants who had seen the injury film gave a mean rating of 8.9, with a standard deviation of 2.1. The 16 participants in the control condition had a mean of 7.0 with a standard deviation of 2.4.
H0: Null Hypothesis: (There is no effect of watching a film that either did or did not include a person being injured because of not wearing a seatbelt)
HA: Alternative Hypothesis: (There is positive effect of watching a film that either did or did not include a person being injured because of not wearing a seatbelt)
Pooled Standard Deviation is given by:
Test Statistic is given by:
t = (8.9 - 7.0)/0.7973
= 2.3832
Take = 0.05
ndf = n1 + n2 - 2 = 16 + 16 - 2 = 30
One Tail - Right Tail Test
From Table, critical value of t = 1.6973
Since the calculated value of t = 2.3832 is greater than critical value of t = 1.6973, the difference is significant. Reject null hypothesis.
Conclusion:
The data support the claim that there is positive effect of
watching a film that either did or did not include a person being
injured because of not wearing a seatbelt.