Psyc Chapter 4 quiz

A researcher selects all of the possible samples with n = 7 scores from a population and computes the sample variance, dividing by n - 1, for each sample. If the population variance is σ2 = 9, then what is the average value for all of the sample variances? a. 9 b. greater than 9 c. less than 9 d. impossible to determine

a

A teacher has given a test to a group of students. The set of scores is: 78, 79, 79, 81, and 83. Find the sample variance for this group of tests scores. a. 4 b. 2.24 c. 3.4 d. 80

A

researcher was asked to provide the standard deviation for a sample of fish weights. The researcher originally reported a standard deviation of 12.3 grams. However, upon closer investigation, she discovered that her scale was 1.1 grams off, and that each fish was actually 1.1 grams heavier than originally reported. What is the new standard deviation? a. 12.3 b. 13.4 c. 15.53 d. It is impossible to tell without knowing the original weights.

A

What is the range for the set of scores: 7, 8, 11, 15, 17, 20? a. 20 b. 1 or 2 c. 7 d. 13 or 14

D

When is the population standard deviation greater than the population variance? a. when the variance is greater than 1 b. The standard deviation is never greater than the variance. c. when the variance is negative d. when the variance is less than 1

D

A researcher selects all of the possible samples with n = 8 scores from a population and computes the mean, dividing by n, for each sample. If the population mean is μ= 14, then what is the average value for all of the sample means? a. 14 b. greater than 14 c. less than 14 d. impossible to determine

A

Under what circumstances would a score that is below the mean by 3 points appear to be very far from the mean? a. When the mean is much less than 3 b. When the mean is much greater than 3 c. When the standard deviation is much greater than 3 d. When the standard deviation is much less than 3

D

Which of the following is a true statement? a. Samples tend to be less variable than their populations. b. Samples tend to be more variable than their populations. c. Samples and their populations tend to have the same variability. d. None of the above is true.

A

Which of the following sets of scores has the least variability? a. 16, 17, 18, 19, 20 b. 5, 7, 8, 9, 12, 13 c. 1, 2, 3, 10, 11, 12 d. 20, 22, 25, 30,31

A

A scientist collected a sample of data of cactus heights. The data was rounded to the nearest half foot. If the minimum score was 3.5 feet and the range was 4 feet, what was the maximum score? a. 7.25 feet b. 7.5 feet c. 7 feet d. 8 feet

C

Find the population variance and standard deviation for the following ages of children in a family: 1, 3, 5, 7, 8, 11, 14. a. σ = 122, σ2= 11.05 b. σ = 17.43, σ2= 4.17 c. σ = 4.17, σ2= 17.43 d. σ = 11.05, σ2= 122

C

In the context of inferential statistics, the variance that exists in a set of sample data is often classified as ______________. a. standard deviation b. mean variance c. error variance d. bimodal variance

C

The following is a sample of IQs from a population. Find the sample standard deviation to two decimal places. PIC a. 212.17 b. 14.57 c. 15.95 d. 254.4

C

When is the standard deviation of a set of scores equals to 0? a. when the variance of the scores is negative b. when there are only two scores in the set c. when the range of the scores is 0 d. The standard deviation is never 0. It is always positive.

C

Which of the following is a valid formula for calculating the sum of square deviations? PIC a. I only b. II only c. I and II only d. II and III only

C

Which of the following is true for the quantity ∑(X - μ)? a. This is the variance, and it is sometimes positive. b. This is the variance, and it is always positive. c. This is the sum of the deviations, and it is always 0. d. This is the standard deviation, and it is always positive.

C

A sample has five scores, but only four of them are known. However, the sample standard deviation is s = 3, and the mean is M = 4. If the four known scores are 1, 1, 5, and 8, which is a possibility for the fifth score? 3 4 5 a. I only b. III only c. II only d. I and III

b

An unbiased statistic is one in which ... a. the average value of the statistic is less than the population parameter. b. the average value of the statistic is greater than the population parameter. c. the average value of the statistic is equal to the population parameter. d. the average value of the statistic is either greater than or less than the population parameter.

c

Each score in a set of data is multiplied by 5, and then 7 is added to the result. If the original mean is 8 and the original standard deviation is 2, what are the new mean and new standard deviation? a. μ = 40, σ = 10 b. μ = 47, σ = 17 c. μ = 47, σ = 10 d. μ = 47, σ = 9

c

A scientist collects a sample of honeybees from a hive. He weighs the honeybees in grams and calculates the standard deviation to be 0.002 grams. If there are 1000 milligrams in one gram, what is the standard deviation in milligrams? a. 0.0002 b. 0.002 c. 0.02 d. 2

d