Deck 14: Descriptive Data Analysis

Question 1

Select the false statement below.

A) The classification of a variable (nominal, ordinal, etc.) has an influence on which descriptive statistics are calculated.
B) Descriptive statistics are used to describe characteristics of a set of scores.
C) Data that are at least interval are desirable because many descriptive statistics can be applied to the data.
D) Classifying people in regard to their gender yields ordinal data.
E) Inferential statistics are used when a sample is used to represent a population.

Answer 1

D

Question 2

Select the false statement below.

A) A measure of central tendency may be calculated to condense a large amount of data into a simple descriptive value.
B) To adequately describe the performance of a group of individuals, a measure of central tendency and variability is needed.
C) Fifty percent of the scores are below the mean.
D) The median has 50% of the scores above it.
E) To calculate the median, the data can be less than interval.

Answer 2

C

Question 3

A researcher reported that for 100 college students, the mean was 80 and the standard deviation was 12.6. How is the standard deviation best interpreted?

A) The variability of the scores around the mean was 12.6.
B) The variability of the scores from each other was 12.6.
C) The minimum value is 0, so 12.6 is a large standard deviation.
D) All of the scores were within 12.6 of the mean (i.e., 67.4-92.6).
E) The score of a person is expected to deviate 12.6 from one time to another.

Answer 3

A

Question 4

Select the true statement concerning percentiles and percentile ranks.

A) If a person has scores on several different measures, his or her mean percentile rank is a good indication of overall ability.
B) If for a 200-point test administered to 60 students the percentile rank of the score 57 is 25, this indicates that 25% of the scores are below 57.
C) If a sit-up test was administered to 75 children and 20% of the children did 25 sit-ups, the percentile rank of the score 25 would be 20.
D) The 86th percentile is the score at or below which 86% of the group scored.
E) Percentile ranks are seldom used because they are difficult to interpret.

Question 5

A researcher determined that the correlation between height in inches and 50-yard-dash time in seconds for 123 eleven-year-old boys in a city recreation program was -0.51. Which of the following statements is the best interpretation of this finding?

A) As height increases, this causes speed to decrease.
B) Tall boys run faster than short boys over 50% of the time.
C) There is some tendency for dash scores to decrease as height increases.
D) There is a very poor relationship between height and dash scores because the correlation is negative.
E) The taller the person, the larger his dash score tends to be.

Question 6

Select the false statement below.

A) A correlation coefficient of -0.98 indicates a great deal of relationship.
B) When calculating r, it is assumed that there is a linear relationship between the two measures.
C) If the correlation between two variables is 0.78, this indicates that if one variable increases, the other variable will increase.
D) One indicator of the goodness of a simple linear prediction equation is a correlation coefficient.
E) If more than one predictor variable is used, it is a multiple prediction situation, and R is one of the indications of the goodness of the prediction equation.

Question 7

Select the false statement concerning the range.

A) The range can be calculated with any classification of data.
B) The range is quick to calculate.
C) The range is the difference between the largest and smallest score.
D) The range and mode are often reported together.
E) The range is a stable and trustworthy measure of score variability.

Question 8

When the data distribution is skewed, which of the following measures should be used to measure central tendency?

A) Mean
B) Median
C) Mode
D) Trimmed mean

Question 9

When the data distribution is normal, which of the following measures should be used to measure variability?

A) Variance
B) Range
C) Standard deviation
D) Interquartile range

Question 10

The mean of T-score distribution is:

A) 50.
B) 100.
C) 10.
D) 0.