PSY 555 Homework 7

Chapter 4:
#3,4,5,7,9,13,14,15,17,20 (draw and shade the distribution when applicable and
show all steps of the hypothesis test)

1. If a researcher normally uses an alpha level
of .01, but this time used an alpha level of

.05,
what does this do to the amount of power?
How does this affect the risk of a Type I error?

2. A researcher is trying to assess the effects
of drug use on IQ. For the population,
the

average
IQ is _{}=100 and _{}=15. The following
data consists of IQ scores for a sample of cocaine addicts:

85,
90, 99, 103, 100, 86, 97, 83, 101, 91, 87

Do
the IQ scores of cocaine addicts significantly differ from those of the
population? Test at the .01 level of
significance and show all four steps of the hypothesis test.

3. A researcher at a drug company is testing the
effectiveness of a new drug that slows down

the
progression of AIDS. Should the
researcher examine his data using a .05 or .01 level of significance? Justify your answer with regards to the risks
of Type I and Type II errors.