A family therapist states that all parents in America talk to their teenagers an average of 17 minutes per week. A psychologist decides to test this by collecting data from a sample of 9 parents on how much time they spend talking to their teenagers per week. Alpha .05, 2-tailed.

Question

A family therapist states that all  parents in America talk to their teenagers an average of 17 minutes per week. A psychologist decides to test this by collecting data from a sample of 9 parents on how much time they spend talking to their teenagers per week. Alpha .05, 2-tailed. 
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A. Give calculated score and critical score.
B. Do the psychologists data differ significantly from what the family therapist stated?
C. Is the family therapists claim an overestimate or an underestimate of actual time spent talking to children, compared to the sample size.

PsyDAG · Answer

Calculate mean and standard deviation (SD) for your sample.

Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√(n-1)

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to that Z score.