# Statistics

Statistics and Methods I

Homework Hypothesis Testing

1.
List the five steps of hypothesis testing, and explain the procedure and logic of each.

2.
A sample of rats in a laboratory is given an experimental treatment intended to make them learn a maze faster than other rats.  State (a) the null hypothesis and (b) the research hypothesis.

3.
(a) What is a comparison distribution?  (b) What role does it play in hypothesis testing?

4.
What can you conclude when (a) a result is so extreme that you reject the null hypothesis and (b) a result is not very extreme so that you cannot reject the null hypothesis?

5.
What is a Nondirectional hypothesis test?

6.
What is a two tailed test?

7.
Why do you use a two tailed test when testing a Nondirectional hypothesis?

8.
A researcher predicts that making people hungry will affect how well they do on a coordination test.

A

randomly selected person is asked not to eat for 24 hours before taking a standard coordination test and gets a score of 400.  For people in general of this age group and gender, tested under normal conditions, coordination scores are normally distributed with a mean of 500 and a standard deviation of 40.  Using the

.01

significance level, what should the researcher conclude?

9.
For each of the following, (a) state which two populations are being compared, (b) state the research hypothesis, (c) state the null hypothesis, and (d) say whether you should use a one-tailed or two-tailed test and why?

i.
In an experiment, people are told to solve a problem by focusing on the details.  Is the speed of solving the problem different for people who get such instructions compared to the speed for people who are given no special instructions?

ii.
Based on anthropological reports in which the statu of women is scored on a 10 point scale, the mean and standard deviation across many cultures are known.  A new culture is found in which there is an unusual family arrangement.  The status of women is also rated in this culture.  Do cultures with the unusual family arrangement provide higher status to women than cultures in general?

iii.
Do people who live in big cities develop more stress-related conditions than people in general?

10.
Based on the information given for each of the following studies, decide whether to reject the null hypothesis.  For each, give (a) the Z-score cutoff (or cutoffs) on the comparison distribution at which the null hypothesis should be rejected, (b) the Z score on the comparison distribution for the sample score, and (c) your conclusion.  Assume that all populations are normally distributed.

A

5 1 7 .05

5 1 7 .01

5 1 7 .01 2

 Population Study µ σ Sample Score p Tails of Test 5 1 7 .05 1 (high predicted B 2 C 1 (high predicted) D