Question

Experimenter bias refers to the phenomenon that data tends to comes out in the desired direction even for the most conscientious experimenters. A social psychologist hypothesizes the opposite phenomenon. In a study, the psychologist tells a sample of students that they will be experimenters in study that investigates the impact of caffeine on cognition. The experimenters are told that all subjects will be given caffeine an hour before solving arithmetic problems. However, half of the experimenters are told that caffeine will lead to better performance and the other half are told nothing. The experimenters are then asked to grade the arithmetic problems. What can the psychologist conclude with an α of 0.05? Below are the grades that they gave.

told nothing	leads to better performance
18 15 21 12 17 14 21 24	12 14 18 8 14 17 20 10

a) What is the appropriate test statistic?
---Select--- na z-test One-Sample t-test Independent-Samples t-test Related-Samples t-test

b)
Condition 1:
---Select--- told nothing grades told caffeine leads to better performance the phenomenon experimenter bias
Condition 2:
---Select--- told nothing grades told caffeine leads to better performance the phenomenon experimenter bias

c) Compute the appropriate test statistic(s) to make a decision about H₀.
(Hint: Make sure to write down the null and alternative hypotheses to help solve the problem.)
critical value =  ; test statistic =  
Decision:  ---Select--- Reject H0 Fail to reject H0

d) If appropriate, compute the CI. If not appropriate, input "na" for both spaces below.
[  ,  ]

e) Compute the corresponding effect size(s) and indicate magnitude(s).
If not appropriate, input and/or select "na" below.
d =  ;  ---Select--- na trivial effect small effect medium effect large effect
r² =  ;  ---Select--- na trivial effect small effect medium effect large effect

f) Make an interpretation based on the results.

Experimenters that were told nothing gave significantly higher grades than experimenters that expected a good performance.Experimenters that expected a good performance gave significantly higher grades than experimenters that were told nothing.    There was no significant grade difference between experimenters that expected a good performance and those that were told nothing.

Answer 1