EC Quiz Questions - Exam 1

Question 1

T or F
Population parameters are often used to estimate sample statistics.

Answer 1

False

Question 2

T or F
If the values are on an interval scale, the difference between –20 and –10 is the same as the difference between 20 and 30.

Answer 2

True

Question 3

T or F
Inferential statistics are required for descriptive statistics.

Answer 3

False

Question 4

T or F
The day of the week (Monday, Tuesday, etc.) is a discrete variable.

Answer 4

True

Question 5

In karate, a student’s skill level is indicated by the color of their belt (white, yellow, … black). What type of variable is belt color?

A. Interval
B. Ordinal
C. Categorical
D. Ratio

Answer 5

B. Ordinal

Question 6

If X has a standard normal distribution, which of the following values of x is farthest from the mean?

A. –2.3
B. –0.2
C. 1.8
D. 1.0

Answer 6

A. –2.3

Question 7

The following data sets all have the same mean (5.5). Without doing any calculations, which of the data sets has the smallest sample standard deviation?

{4, 4, 4, 4, 7, 7, 7, 7}
{4, 4, 5, 5, 6, 6, 7, 7}
{2, 2, 2, 2, 9, 9, 9, 9}
{2, 3, 4, 5, 6, 7, 8, 9}

Answer 7

{4, 4, 5, 5, 6, 6, 7, 7}

Question 8

Which of the following is true for a smooth, unimodal distribution with obvious positive skew?

Mean > median > mode
Mode > mean > median
Mode > median > mean
Median > mean > mode

Answer 8

Mean > median > mode

Question 9

Which of the following measures of variability is least susceptible to outliers?

Interquartile range
Range
Standard deviation

Answer 9

Interquartile range

Question 10

If a standardized test has a normal distribution with a mean of 50 and a standard deviation of 10, what z score corresponds to a score of 35?

A. –1.5
B. –15
C. 35
D. –0.67

Answer 10

A. –1.5

Question 11

Which of the following is true of the sample mean?

A. It is the same as the population mean for the same variable.
B. It minimizes the sum of the absolute values of the deviations of the
individual values.
C. It minimizes the sum of the the deviations of the individual values.
D. It minimizes the sum of the squares of the deviations of the individual
values.

Answer 11

D. It minimizes the sum of the squares of the deviations of the individual values.

Question 12

T or F
For an interval or ratio variable X, the sample variance of the z scores is 1 for any sample.

Answer 12

True

Question 13

Dutch men are some of the tallest in the world. In one very large study, the mean was 183.8 cm and the standard deviation was 7.1 cm. Let’s assume that the population parameters have these same values and that height is normally distributed. Which of the following lines of R code will tell you the percentile of a Dutch man who is 179 cm tall?

A. pnorm(179, mean=183.8, sd=7.1)
B. 1 – pnorm(179, mean=183.8, sd=7.1)
C. qnorm(179, mean=183.8, sd=7.1)
D. 1 – qnorm(179, mean=183.8, sd=7.1)

Answer 13

A. pnorm(179, mean=183.8, sd=7.1)

Question 14

Which one of the following statements about probability density functions (PDFs) is FALSE?

A. The total area under the PDF is different for different distributions.
B. For two distributions of the same type (e.g., normal distributions),
the one that has the smaller standard devition will have a taller PDF.
C. Multiplying all of the scores by a constant leaves the area under
the PDF unchanged.
D. Areas under a PDF correspond to probabilities.

Answer 14

A. The total area under the PDF is different for different distributions.

Question 15

In a boxplot, what do (a) the box, (b) the line across the box, and (c) any points beyond the “whiskers” represent (in that order)?

A. (a) the first and third quartiles, (b) the mean, and (c) outliers
B. (a) the first and third quartiles, (b) the median, and (c) the minimum
and maximum values
C. (a) plus or minus one standard deviation, (b) the mean, and (c) outliers
D. (a) the first and third quartiles, (b) the median, and (c) outliers

Answer 15

D. (a) the first and third quartiles, (b) the median, and (c) outliers