# Project #37195 - STATISTICS

STAT 625

Summer 2014

Quiz # 4

1.) The null hypothesis usually represents the

 a. theory the researcher would like to prove b. preconceived ideas of the researcher c. perceptions of the sample population d. status qu0

2.) If we reject the null hypothesis, we conclude that:

 a. there is enough statistical evidence to infer that the alternative hypothesis is true b. there is not enough statistical evidence to infer that the alternative hypothesis is true c. there is enough statistical evidence to infer that the null hypothesis is true d. the test is statistically insignificant at whatever level of significance the test was conducted at

3.) A two-tailed test is one where:

 a. results in only one direction can lead to rejection of the null hypothesis b. negative sample means lead to rejection of the null hypothesis c. results in either of two directions can lead to rejection of the null hypothesis d. no results lead to the rejection of the null hypothesis

4.) A low p–value provides evidence for accepting the null hypothesis and rejecting the alternative.

True

False

5.) If we perform a two-tail independent samples t-test, our null hypothesis is about:

 a. Equality of two sample means b. Difference of two sample means c. Equality of two population mean d. The mean of the population difference

6.) The rejection region is the set of sample data that leads to the rejection of the alternative hypothesis.

True

False

7.) If a null hypothesis about a population mean is rejected at the 0.025 level of significance, then it must also be rejected at the 0.01 level.

True

False

8.) If the p-value for the “equality of variances test” is greater than the alpha value set for that test, the appropriate test to choose if we were comparing the difference of two means is:

 a. Equal variances independent-sample t-test b. Unequal variances independent-sample t-test c. Paired-samples t-test d. None of the above

9.) have sample data on five conferences and I would like to use it all for the test. I would test this hypothesis using:

 a. Paired-samples t-test with an equal sample of players from each conference b. Independent-samples t-test c. ANOVA d. Single-sample t-test on the difference in heights

10.) In testing the null hypothesis that the population proportion is 0.75, at the 5% significance level, if the sample size is 10 and the sample proportion is 0.45, which one would be the appropriate conclusion?  Note: z(0.975)=1.96

 Reject the null hypothesis Fail to reject the null hypothesis Reject the alternative hypothesis Fail to reject the alternative hypothesis

11.) A test for independence is applied to a contingency table with 4 rows and 4 columns. The degrees of freedom for this chi-square test must equal 9.

True

False

12.) The owner of a popular Internet-based auction site thinks that more than half of the people who sell items on her site are women. To test this hypothesis, the owner sampled 1000 customers who sold items on her site and she found that 53% of the customers sampled were women. The calculated z-statistic is 1.9 with p-value of 0.028. What is the correct alternative hypothesis form for testing this hypothesis and what would be the owner’s conclusion at 5% significance level?

 a. H(a):p < 0.5 - She fails to conclude that women make up more than 50% of her customers b. H(a):p > 0.5 - She can conclude that women make up more than 50% of her customers c. H(a):p>=0.5- She fails to conclude that women make up more than 50% of her customers d. H(a):p<=0.5 - She can conclude that women make up more than 50% of her customers

13.) Suppose we get the following significant results from a regression analysis where we used “productivity” measured on a 0-100 scale as the dependent variable and “seniority” measured in years working at the company as the independent variable. Which choice is one of the correct interpretations where the intercept of the regression line is 96 and the slope of the regression line is -2.5:

 a. For every additional year spent working at the company, the average productivity increases by 2.5 b. For every additional year spent working at the company, the average productivity decreases by 2.5 c. For every additional year spent working at the company, the average productivity increases by 96 d. For every additional year spent working at the company, the average productivity decreases by 96

14. ) A sport preference poll yielded the following data for men and women. In using the 5% significance level to test whether sport preference and gender are independent, what are the calculated figures of the test statistic and the p-value?

 Basketball Football Soccer Men 20 45 30 Women 20 15 25

 a. t-statistic: 5.991  ,  p-value: 0.049 b. chi-square: 7.957  ,  p-value: 0.0187 c. t-statistic; 7.957  ,  p-value: 0.05 d. chi-square: 5.991  ,  p-value: 0.05

 Subject Mathematics Due By (Pacific Time) 08/04/2014 9:30pm
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