When the sample sizes are equal, the pooled variance of the two samples is the ____________________ ...

When the sample sizes are equal, the pooled variance of the two samples is the ____________________ of the two sample variances.
 Fill in the blank(s) with correct word

Q. 2

The time series component that reflects the irregular changes in a time series that are not caused by any other component, and tends to hide the existence of the other more predictable components, is called random variation.
  Indicate whether the statement is true or false

Q. 3

Suppose we randomly selected 250 people, and on the basis of their responses to a survey we assigned them to one of two groups: high-risk group and low-risk group. We then recorded the blood pressure for the members of each group. Such data are called:
 a. observational. c. matched.
  b. experimental. d. None of these choices.

Q. 4

One of the simplest ways to reduce random variation is to smooth the time series using moving averages and exponential smoothing.
  Indicate whether the statement is true or false

Q. 5

A political analyst in Hawaii surveys a random sample of registered Democrats and compares the results with those obtained from a random sample of registered Republicans. This would be an example of:
 a. independent samples.
  b. dependent samples.
  c. independent samples only if the sample sizes are equal.
  d. dependent samples only if the sample sizes are equal.