ADVANCED STATISTICS

p. 377, 2.

2. A dorm has 86 men and 132 women living in it.  The number of men and women at the college is 753 and 1,063, respectively.  The dean of students wonders if this dorm’s sex ration reflects the sex ratio of the college.

a. State the research hypothesis

b. What is the df study?

c.  Complete the following table:

Men                                                                             Women

_________________________________                                   ________________________________________

No. Observed               No. Expected                           No. Observed               No. Expected

d. Calculate X^2.

e.  Interpret the result at the .05 error of level.  Is the research hypothesis supported?

p. 382, 2.

2. You read a report saying that people who buy antiques online tend to be more highly educated than people who buy antiques at live auctions.  What are the rwo variables in this study?

p. 402, 2.

2. Exercise 3 in Module 20 examined whether adding a fragrance to a window cleaner led people to believe that it cleans better than unscented product.  There were 12 subjects in each group: scented or unscented.  The mean cleaning effectiveness rating for the group getting the scented cleaner was 7.42. The meaning cleaning effectiveness rating for the group getting unscented was 6.00.  The standard deviation for cleaning effectiveness ratings across all subjects is 1.369. A t test showed that the scented cleaner was rated as a significant more effective cleaner (t=2.84, a <.01).

a.       Calculate the effect size for this study, using both Cohen’s d and effect size r.

b.      Interpret the result: Was there a practical difference in cleaning effectiveness between scented and unscented cleaners?

p. 414, 8. (directions for this set of practice: Use Power Tables 33.1, 33.2, and 33.3)

8. You are designing a study to be evaluated with a two-sample nondirectional independent t test at a = .05.  You want .90 power.  You expect Cohen’s d to be about .40.  How many subjects will you need peer group?

p. 415, 14. (directions for this set of practice: Use Power Tables 33.1, 33.2, and 33.3)

14. You are designing a three group study to be evaluated with a one-way Nova at

a =.05. You expect effect size n to be about .29.  How many subjects will you need per group for .80?

p. 419, 4.

4.  Which of these studies might be analyzed with a correlation?

a. The which group has a higher reading comprehension level-dyslexic children versus ADHD (attention deficit hyperactivity disorder) children

b.  The amount of religious commitment and frequency of attendance at religious services

c.  The number of doctor visits and income level

d.  The soft drink preferences of college students

p.425, 12.

12.  For each of the following, indicate whether the expected relationship between the two variables will be positive (+), negative (-), or zero:

a.       size of house and size of electric bill

b.      height of parents and height of children

c.        air humidity level and people’s energy level

d.      number of books read per year and age at which got first eyeglasses

e.       hours spent at the beach and depth of tan