Biology Forums - Study Force

In testing the difference between two population means for which the population variances are unknown and not assumed to be equal, two independent samples are drawn from the populations. Which of the following tests is appropriate?
 a. z-test c. unequal variances t-test
  b. pooled-variances t-test d. None of these choices.

Q. 2

We calculate the three-period moving average for a time series for all time periods except the first period.
  Indicate whether the statement is true or false

Q. 3

Two independent samples of sizes 25 and 35 are randomly selected from two normal populations with equal variances (assumed to be unknown). In order to test the difference between the population means, the test statistic is:
 a. a standard normal random variable.
  b. approximately standard normal random variable.
  c. Student t-distributed with 58 degrees of freedom.
  d. Student t-distributed with 33 degrees of freedom.

Q. 4

The time series component that reflects a long-term, relatively smooth pattern or direction exhibited by a time series over a long time period is called seasonal.
  Indicate whether the statement is true or false

Q. 5

In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you:
 a. round to the nearest integer.
  b. change the sample sizes until the number of degrees of freedom becomes an integer.
  c. assume that the population variances are equal, and then use df = n1 + n2 - 2.
  d. None of these choices.

Q. 6

Seasonal variation is one of the four different components of a time series. These are cycles that occur over short repetitive calendar periods and, by definition, have duration of less than one year.
  Indicate whether the statement is true or false

Ans. #1

C

Ans. #2

F

Ans. #3

C

Ans. #4

F

Ans. #5

A

Ans. #6

T

All are answered correctly

Happy to help