Question 1:

For each of the 6 examples (a-f), you need to provide the following answers:

1. the conditions of the independent variable (if you want to name the IV too, that's fine, but make sure you list the conditions)
2. the scale of measurement for the IV
3. the dependent variable
4. the scale of measurement for the DV
5. the measure of central tendency you would use in this specific example
6. the measure of variability you would use in this specific example
   (NOTE for 5 & 6:  make sure you consider the variables that influence your choice for the measures of central tendency and variability)
7. which scores you would use to compute the measure of central tendency and variability

1. We test whether participants laugh longer (in seconds) to jokes told on a sunny or rainy day.
2. We test babies whose mothers were or were not recently divorced, measuring whether the babies lost weight, gained weight, or remained the same.
3. We compare a group of adult children of alcoholics to a group whose parents were not alcoholics. In each, we measure the participants’ income.
4. We count the number of creative ideas produced by participants who are paid 5, 10, or 50 cents per idea.
5. We measure the number of words in vocabulary of 2-year-olds as a function of whether they have 0, 1, 2, or 3 older siblings.
6. We compare people 5 years after they have graduated from either high school, a community college, or a four-year college. Considering all participants at once, we rank order their income.

Question 2:

In a population, mu (μ) = 100 and σ _x = 25. A sample ( N = 150) has x̄ = 102. Using two tails of the sampling distribution and the .05 criterion:

(a) What is the critical value?

(b) Is this sample in the region of rejection? How do you know?

(c) What does this indicate about the likelihood of this sample occurring in this population?

(d) What should we conclude about the sample?

Question 3:

On a standard test of motor coordination, a sports psychologist found that the population of average bowlers had a mean score of 24, with a standard deviation of 6. She tested a random sample of 30 bowlers at Fed’s Bowling Alley and found a sample mean of 26. A second random sample of 30 bowlers at Ethel’s Bowling Alley had a mean of 18. Using the criterion of p = .05 and both tails of the sampling distribution, what should she conclude about each sample’s representativeness of the population of average bowlers?

Question 4:

Foofy computes the x̄ from data that her professor says is a random sample from population Q . She correctly computes that this mean has a z -score of +41 on the sampling distribution for population Q . Foofy claims she has proven that this could not be a random sample from population Q . Do you agree or disagree? Why?

Question 5 :

For each study in "question 11", indicate whether a one- or a two-tailed test should be used and state the H ₀ and H _a . Assume that μ = 50 when the amount of the independent variable is zero.

"Question 11" – Describe the experimental hypotheses and the independent and dependent variables when we study:

1. Whether the amount of pizza consumed by college students during finals week increases relative to the rest of the semester.
2. Whether breathing exercises alter blood pressure.
3. Whether sensitivity to pain is affected by increased hormone levels.
4. Whether frequency of day-dreaming decreases as a function of more light in the room.

Question 6 :

We ask whether attending a private school leads to higher or lower performance on a test of social skills. A sample of 100 students from a private school produces a mean of 71.30 on the test, and the national mean for students from public schools is 75.62 (σ _x = 28.0).

1. Should we use a one-tailed or a two-tailed test? Why?
2. What are H ₀ and H _a ?
3. Compute z _obt .
4. With α = .05, what is z _crit ? (α = criterion probability / greek letter alpha)
5. What should we conclude about this relationship?

Question 7 :

1. In the above question, what is the probability that we made a Type I error? What would be the error in terms of the independent and dependent variables?
2. What is the probability that we made a Type II error? What would be the error in terms of the independent and dependent variables?

Question 8 :

We ask if the attitudes toward fuel costs of 100 owners of hybrid electric cars (x̄ = 76) are different from those on a national survey of owners of non-hybrid cars (μ = 65, σ _{x =} 24). Higher scores indicate a more positive attitude.

1. Is this a one- or two-tailed test?
2. In words what is H ₀ and H _a ?
3. Perform the z -test.
4. What do you conclude about attitudes here?
5. Report your results in the correct format.

Question 9 :

We measure the self-esteem scores of a sample of statistics students, reasoning that this course may lower their self-esteem relative to that of the typical college student (μ = 55, σ _{x =} 11.35). We obtain these scores:

44 55 39 17 27 38 36 24 36

1. Summarize your sample data.
2. Is this a one-tailed or two-tailed test? Why?
3. What are H ₀ and H _a ?
4. Compute z _obt .
5. With α = .05, what is the z _crit ? (α = criterion probability / greek letter alpha)
6. What should we conclude about the relationship here?

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Solution: The downloadable solution consists of 11 pages, 1926 words and 8 charts.
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