In constructing a confidence interval estimate for the difference between two population proportions, we:
a. pool the population proportions when the populations are normally distributed.
b. pool the population proportions when the population means are equal.
c. pool the population proportions when they are equal.
d. never pool the population proportions.
Q. 2Which of the following equations deseasonalize a time series, where T, C, S, and R are respectively the trend, cyclical, seasonal, and random variation components of the time series?
a. (T C S R) / T = C S R
b. (T C S R) / C = T S R
c. (T C S R) / S = T C R
d. (T C S R) / R = T C S
Q. 3For testing the difference between two population proportions, the pooled proportion estimate is found by taking:
a. the proportion of successes from sample 1 plus the proportion of successes from sample 2.
b. the total number of successes in both samples divided by the total of both sample sizes.
c. the difference between the proportion of successes in each sample.
d. None of these choices.
Q. 4Which of the following will be reflected by deseasonalized time series?
a. Trend effects
b. Cyclical effects
c. Random variation
d. All of these choices are true.
Q. 5The pooled proportion estimate is used when:
a. the proportion of successes from sample 1 equals the proportion of successes from sample 2.
b. the total number of successes in both samples divided by the total of both sample sizes equals 1.
c. the null hypothesis states that the two population proportions differ by some non-zero number.
d. None of these choices.
Q. 6The level of construction employment in West Virginia is lowest during the winter. A model designed to forecast construction employment in Charleston should use:
a. a time trend
b. a moving average
c. seasonal indicator variable
d. an autoregressive model
Q. 7For testing the difference between two population proportions, the pooled proportion estimate should be used to compute the value of the test statistic when the:
a. populations are normally distributed.
b. sample sizes are small.
c. null hypothesis states that the two population proportions are equal.
d. samples are independently drawn from the populations.
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