Quiz about Chi-Square (Ch 11)

Question 1

Find the degrees of freedom.

Accepted Answer

6

Answer

4

Answer

5

Answer

7

Question 2

The table shows the number or babies born on each day of the week.  Is there evidence that births are more likely on specific days of the week?

Accepted Answer

yes, the p value is less than .05

Answer

yes, the p value is greater than .05

Answer

no, the p value is less than .05

Answer

no, the p value is greater than .05

Question 3

What must be true about the expected values in a chi square test?

Accepted Answer

greater than or equal to 5

Answer

greater than or equal to 2

Answer

greater than or equal to 10

Answer

greater than or equal to 30

Question 4

Which test would you use to see if the distribution of music that Californians listen to is the same as that of Nevadans?  900 Californians and 600 Nevadans were surveyed.

Accepted Answer

Chi-Square Test for Homogeneity

Answer

Chi-square Goodness of Fit Test

Answer

Chi-Square Test for Independence/Association

Answer

Not a Chi-square test

Question 5

Which test would you use .... In 1974, each acre of the Tahoe basin was assessed to see what condition the soil was in.  23% of acres were of type I, 32% were of type II, 41% were of type III, and 16% were of type IV.  This year the region was assessed again and the number of each type were again determined.

Accepted Answer

Chi-square Goodness of Fit Test

Answer

Chi-Square Test for Homogeneity

Answer

Chi-Square Test for Independence/Association

Answer

Not a Chi-square test

Question 6

Which test would you use to see if people on computers and people on handhelds use the same Internet search engines?  1000 web searches from a computer and 1500 web searches from a hand held were tracked to see what search engine was used.

Accepted Answer

Chi-Square Test for Homogeneity

Answer

Chi-square Goodness of Fit Test

Answer

Chi-Square Test for Independence/Association

Answer

Not a Chi-square test

Question 7

Which test would you use to see if shoe brand preferences changed between last year and this year?  1000 people were observed this year and last year to see what brand of shoe they were wearing.

Accepted Answer

Chi-Square Test for Homogeneity

Answer

Chi-square Goodness of Fit Test

Answer

Chi-Square Test for Independence/Association

Answer

Not a Chi-square test

Question 8

Which test would you use to see whether the fans that buy tickets are demographically the same as the general population of the city.  Currently 42% are Caucasian, 35% are Hispanic, 12% are African American, 8% are Asian, and the rest are defined as other.

Accepted Answer

Chi-square Goodness of Fit Test

Answer

Chi-Square Test for Homogeneity

Answer

Chi-Square Test for Independence/Association

Answer

Not a Chi-square test

Question 9

What are the expected counts of a female who likes Pepsi?

Accepted Answer

10.5

Answer

11

Answer

14.5

Answer

6.3

Question 10

A chi-square test is used to test whether a 0 to 9 spinner is "fair" (that is, the outcomes are all equally likely).  The spinner is spun 100 times, and the results are recorded.  The degrees of freedom for the test will be

Accepted Answer

9

Answer

8

Answer

10

Answer

99

Question 11

A chi-square test is used to test whether a 0 to 9 spinner is "fair" (that is, the outcomes are all equally likely).  The spinner is spun 100 times, and the results are recorded.  The expected counts for spinning a 5 will be

Accepted Answer

10

Answer

5

Answer

11.1

Answer

20

Question 12

Recent revenue shortfalls in a midwestern state led to a reduction in the state budget for higher education.  To offset the reduction, the largest state university proposed a 25% tuition increase.  It was determined that such an increase was needed simply to compensate for the lost support from the state.  Separate random samples of 50 freshmen, 50 sophomores, 50 juniors, and 50 seniors from the university were asked whether they were strongly opposed to the increase, given that it was the minimum increase necessary to maintain the university's budget at current levels.  The results are in the table provided.  Why hypotheses would be appropriate for performing a chi-square test?

Accepted Answer

The null hypothesis is that the distribution of student opinion about the proposed tuition increase is the same for each of the 4 years at the university.  The alternative is that the distribution is different for at least 2 of the 4 years.

Answer

The null hypothesis is that the closer students get to graduation, the less likely they are to be opposed to tuition increases.  The alternative is that how close students are to graduation makes no difference in their opinion.

Answer

The null hypothesis is that the mean number of students who are strongly are opposed is the same for each of the 4 years.  The alternative is that the mean is different for at least 2 of the 4 years.

Answer

The null hypothesis is that year in school and student opinion about the tuition increase in the sample are independent.  The alternative is that these variables are dependent.

Question 13

A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race of the driver. The results are summarized in the table provided. Assuming H₀ is true, the expected number of Hispanic drivers who would receive a ticket is

Accepted Answer

11.84

Answer

10.36

Answer

11

Answer

12

Question 14

All current-carrying wires produce electro-magnetic (EM) radiation.  High-frequency EM radiation is thought to be a cause of cancer.  The lower frequencies are generally assumed to be harmless.  To investigate the relationship between current configuration and type of cancer, researchers visited the addresses of a random sample of children who died of some form of cancer (leukemia, lymphoma, or some other type) and classified the wiring configuration outside the dwelling as either high-current configuration (HCC) or low-current configuration (LCC).  The data is provided in a table.  Which of the following may we conclude, based on the test results?

Accepted Answer

There is not convincing evidence of an association between wiring configuration and the type of cancer that cause the deaths of children in the study.

Answer

There is convincing evidence of an association between wiring configuration and the chance that a child will develop some form of cancer.

Answer

HCC either causes cancer directly or is a major contributing factor to the development of cancer in children.

Answer

There is convincing evidence that HCC does not cause cancer in children.

Question 15

Which statement is NOT correct about the chi-square test statistic?

Accepted Answer

a)A value close to 0 would indicate expected counts are much different from observed counts.

Answer

b)A large value of the test statistic would be in support of the alternative hypothesis.

Answer

c)A small value of the test statistic would indicate evidence supporting the null hypothesis.

Answer

d)The test statistic is the sum of positive numbers and therefore must be positive.

Question 16

: The chi-square statistic is similar to all other test statistics we have discussed  in that it compares observed values to values that would be expected if H0 were true.

Accepted Answer

True

Answer

False

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