Exam 2 Practice Test

Exam 2 Practice Test

This practice exam is based on a test from a previous semester. You are not responsible for material covered in questions 22, 26 or 29. The exam will also have anessay question.

Multiple Choice

Identify the choice that best completes the statement or answers the question. (1.5 Pts each)

____1.If a Z score is 0 then the value of the corresponding raw score would be

a. / 0
b. / the same as the mean of the empirical distribution
c. / the same as the standard deviation of the empirical distribution
d. / probably a negative number

____2.A defining characteristic of the normal curve is that it is

a. / theoretical
b. / positively skewed
c. / negatively skewed
d. / perfectly skewed

____3.The area beyond  2 standard deviations contains approximately what % of the area under the normal curve?

a. / 75%
b. / 50%
c. / 9%
d. / 5%

____4.The Z score table gives the area between a score and the mean. For a Z score of 1.00 that area (in percentages) is

a. / 34.13%
b. / 34.13%
c. / 68.26%
d. / 68.26%

____5.Column C in the normal curve table lists "areas beyond Z". This is the area

a. / below a positive Z score
b. / above a negative Z score
c. / between two positive Z scores
d. / above a positive Z score

____6.The area between the mean and a Z score of +1.50 is 43.32%. This score is less than ____ of the scores in the distribution.

a. / 43.32%
b. / 6.68%
c. / 3.32%
d. / 93.32%

____7.The mean score on a final chemistry exam was 75, and the standard deviation of the scores was 5. If the distribution is normal and your score was 70, what percentage of the scores was lower than yours?

a. / 15.87%
b. / 30.00%
c. / 34.13%
d. / 50.00%

____8.The probability that a randomly selected case will have a score beyond ± 1.00 standard deviation of the mean is

a. / .6826
b. / .5000
c. / .3174
d. / 1/2 of the area of 1 standard deviation

____9.Statistics are to parameters as

a. / samples are to populations
b. / populations are to samples
c. / medians are to standard deviations
d. / percentages are to proportions

____10.Social scientists use inferential statistics to generalize to populations after they have

a. / collected a representative sample
b. / collected all the information possible from the entire population
c. / collected an EPSEM sample from the population of interest
d. / collected at least 100 cases from all possible populations

____11.The fundamental principle of probability sampling is that a sample selected by ____ is very likely to be ____.

a. / EPSEM, representative
b. / stratification, large
c. / telephone polls, cheap
d. / clusters, stratified

____12.Unlike the sample and population distributions, the sampling distribution is

a. / empirical
b. / theoretical
c. / random
d. / EPSEM

____13.The standard error of the mean is the same thing as

a. / the standard deviation of a sample
b. / the standard deviation of a population
c. / the standard deviation of a sampling distribution
d. / the variance of a sample

____14.When we use larger samples (N > 100) we can assume a normal sampling distribution because of

a. / common sense
b. / the Central Limit Theorem
c. / what we know about the population
d. / what we know about the sample

____15.In estimation procedures, as the alpha level decreases, the corresponding Z scores

a. / move closer to the mean of the sampling distribution
b. / move away from the mean of the sampling distribution
c. / become negative
d. / become positive

____16.Which sample size will produce the confidence interval with the smallest width?

a. / 100
b. / 200
c. / 500
d. / 1000

____17.The central problem in the case of one sample hypothesis test is to determine

a. / if a sample is random
b. / if sample statistics are the same as those of the sampling distribution
c. / if parameters are representative of population
d. / if a sample came from a population with a certain characteristic

____18.The null hypothesis in the one sample case is a statement of

a. / agreement with the research hypothesis
b. / rejection
c. / acceptance
d. / no difference

____19.In tests of significance, if the test statistic falls in the critical region, we may conclude that

a. / the population distribution is normal
b. / the null hypothesis can be rejected
c. / the research hypothesis is true
d. / our sample size was too small

____20.If the critical region begins at Z(critical) =  2.56 and the test statistic is  2.50, we

a. / fail to reject the null hypothesis
b. / reject the null hypothesis
c. / cannot make a decision because the test statistic is so close to the critical region
d. / change the alpha level

____21.A sample of people attending a professional football game averages 13.7 years of formal education while the surrounding community averages 12.1. The difference is significant at the .05 level. What could we conclude?

a. / the null hypothesis should be accepted
b. / the research hypothesis should be rejected
c. / the sample is significantly more educated than the community as a whole
d. / the alpha level is too low

____22.In a one-tailed test of hypothesis, the entire ____ should be placed in either the upper or lower tail of the ____

a. / critical area, sampling distribution
b. / sample mean, population distribution
c. / Z score, critical area
d. / sampling distribution, sample distribution

____23.When we decide on a value for alpha, we are

a. / defining the likelihood of accepting the alternative hypothesis
b. / establishing whether the test will be one or two tailed
c. / setting the probability of committing a Type I error
d. / setting the probability of a one-tailed test

____24.When testing for the significance of the difference between a sample mean and a population mean, degrees of freedom are equal to

a. / N  1
b. / N + 1
c. / alpha
d. / 1  alpha

____25.When random samples are drawn so that the selection of a case for one sample has no effect on the selection of cases for another sample, the samples are

a. / dependent
b. / independent
c. / simple
d. / systematic

____26.When conducting hypothesis tests for two sample means, the term 12 in the numerator of the formula reduces to zero because

a. / the standard deviations are calculated first
b. / the tests are conducted at very low alpha levels
c. / the samples are independent as well as random
d. / the null hypothesis is assumed to be true

____27.When testing for the significance of the difference between two sample means, we must first estimate ____ before we can compute the test statistic.

a. / the standard deviation of the sampling distribution
b. / the standard deviations of the samples
c. / the population means
d. / the critical region

____28.For all tests of hypothesis, the probability of rejecting the null is a function of

a. / the size of the observed differences
b. / the alpha level and the use of one- or two-tailed tests
c. / sample size
d. / all of the above

____29.Four test of significance were conducted on the same set of results:

For test 1: alpha = 0.05, two-tailed test.
For test 2: alpha = 0.10, one-tailed test.
For test 3: alpha = 0.01, two-tailed test.
For test 4: alpha = 0.01, one-tailed test.

Which test is most likely to result in a rejection of the null hypothesis?

a. / Test 1
b. / Test 2
c. / Test 3
d. / Test 4

____30.The larger the sample size, the

a. / more important the observed difference
b. / more likely we are to reject the null hypothesis
c. / less likely we are to reject the null hypothesis
d. / lower the Z score

____31.Random samples of 1546 men and 1678 women have been given a scale that measures support of legal abortion. Men average 12.45 and women average 12.46 and the difference is significant at the 0.05 level. What can we conclude?

a. / There is an important difference between men and women on this issue.
b. / Because of the large sample sizes, these results may be statistically significant but trivial.
c. / The difference should be re-tested with a one-tailed test
d. / The difference should be re-tested at a higher alpha level

____32.The ANOVA test is designed for dependent variables that have been measured at

a. / the interval-ratio level
b. / the nominal level
c. / the ordinal level
d. / any level of measurement

____33.ANOVA is appropriate for situations in which

a. / only nominal level variables are involved
b. / we are comparing more than two samples or groups
c. / the independent variable is interval-ration in level of measurement
d. / there are fewer than two samples

____34.A researcher is comparing random samples of white, black, and Hispanic Americans for differences in income, family size, and years of education. Which of the following tests of significance would be appropriate for these situations?

a. / t test for small samples
b. / t test for difference in means
c. / ANOVA
d. / the test for the significance of the difference between sample proportions

____35.If we reject the null hypothesis in a test using analysis of variance, we are concluding that

a. / the populations from which our samples come are different
b. / the variable are independent
c. / the population variances are the same
d. / the sample means are significantly different

____36.The F ratio is equal to

a. / SST  SSB
b. / the "mean square between" divided by the "mean square within"
c. / the "mean square within" minus the "mean square between"
d. / the total variance divided by the mean square between

____37.The sampling distribution for the ANOVA test is

a. / the Z distribution
b. / the t distribution
c. / the F distribution
d. / None of the above

____38.One limitation of the ANOVA test (and all tests of significance) is that

a. / results based on large samples are not reliable
b. / both independent and dependent variables must be at least ordinal in level of measurement
c. / the population variance is extremely unstable and computations may not be accurate
d. / statistical significance is not the same thing as importance in any other sense

Calculations

39) A scale measuring prejudice has been administered to a large sample of respondents. The distribution of scores is approximately normal, with a mean of 31 and a standard deviation of 5. What percentage of the sample had scores above 35?

40) A scale measuring prejudice has been administered to a sample of 100 respondents. The distribution of scores is from a population which is approximately normal, with a mean of 31 and a standard deviation of 5. What is the probability the sample will have a mean less than 30?

42) A researcher has gathered information from a random sample of 178 households. In the sample, there were an average of 2.1 television sets per household with a standard deviation of s=1.0 . give a 95% confidence interval for the number of television sets per household in the population.

Short Answer

For each set of SPSS output, answer the following questions.

1)What is the null hypothesis being tested?

2)What is the alternative hypothesis?

3)What type of test is being conducted, single mean test, independent mean test or ANOVA?

4)Should you reject the null hypothesis?

5)Interpret the test results

6)For single mean tests and independent mean tests only, what does the confident interval represent?

7)For single mean tests and independent mean tests only, is the test one-tailed or 2 tailed at a 95% level of confidence?

8)For ANOVA tests only, which means show significant differences?

SPSS Output Set #1

SPSS Output Set #2

SPSS Output Set #3

Post Hoc Tests

Exam 2 Fall Practice Test

Answer Section

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39. 21.29%

40. 2.33%

41. 95% confident the mean number of television sets in an American household is between 1.95 and 2.25.