Test of Independence

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?

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

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

• 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.

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

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.....

• 10.36

• 11

• 11.84

• 12

What is the χ² _calculated value for the following situation.

• 6.65

• 6.66

• 0.00991

• 1

Find the chi-squared calculated value for the table.

• 0.486170447

• 1.442392006

• 1.45

• 2

Given that a student is male, what is the probability that maths is their favorite?

• 0.491

• 0.225

• 0.443

• .508

The appropriate null hypothesis for performing a chi-square test is that

• equal proportions of female and male teenagers are almost certain they will be married in 10 years.

• there is no difference between the distributions of female and male teenagers' opinions about marriage in this sample.

• there is no difference between the distributions of female and male teenagers' opinions about marriage in the population.

• there is no association between gender and opinion about marriage in the sample.

• there is no association between gender and opinion about marriage in the population.

What is the expected count of a female who likes Pepsi?

• 10.5

• 11

• 14.5

• 6.3

Does the data give evidence of an association between gender and soft drink choice?

• Yes, we reject the null hypothesis.

• No, we fail to reject the null hypothesis

• No, we reject the null hypothesis.

• Yes, we fail to reject the null hypothesis.

• Cannot be determined because the large counts condition is not met.

The degrees of freedom for the chi-square test for this two-way table are

• 4

• 8

• 10

• 20

• 4876