Statistics Proportions Inference for the Difference

A credit card company would like to compare the proportion of people who have poor credit to the proportion of people who think they have poor credit. Which of the following is most appropriate?

• Proportion Z-Test

• Proportion Z-Interval

• 2-Proportion Z-Test

• 2-Proportion Z-Interval

Which of the following is true pertaining to a 2-proportion z-interval?

• There are no restrictions on sample size 

• This interval can be found even if the samples are not random

• The population should be large, relative to each of the sample sizes

• So long as all conditions are met for one sample, you do not need to check conditions for the other sample

What additional condition must be checked for a 2-proportion test or interval compared to a 1-proportion test or interval?

• You must make sure that the samples are random

• You must make sure that the two samples are independent from one another

• You must make sure that the sum of the samples' sizes are smaller than 10% of the whole population

• The conditions are exactly the same

In a past General Social Survey, a random sample of men and women answered the question “Are you a member of any sports clubs?” Based on the sample data, 95% confidence intervals for the population proportion who would answer “yes” are .13 to .19 for women and .247 to .33 for men. Based on these results, you can reasonably conclude that 

• At least 25% of American men and American women belong to sports clubs.

• At least 16% of American women belong to sports clubs. 

• There is a difference between the proportions of American men and American women who belong to sports clubs.

• There is no conclusive evidence of a gender difference in the proportion belonging to sports clubs

The process of drawing conclusions using valid data from samples and making generalizations about a population.

• Validity

• Random Sample

• Sample

• Inferential Statistic

The symbol for the sample proportion is __________.

• Z_c

• p̂

• E

• q

Define the symbol.

• population proportion

• population standard deviation

• sample proportion

• sample size

Select the correct description

• Average Percent

• Population Proportion

• Sample Proportion

• Percent Slope of a Distribution

Should there be more restrictions on handguns? In a pre-Columbine survey, 255 out of 1,020 adults answered in the affirmative; in a 2000 post-Columbine survey, 352 out of 1,100 answered affirmatively. Establish a 90 percent confidence interval estimate of the difference between the proportions of adults in 1995 and 2000 who support more restrictions on handguns.