GRAVETTER_CH02_GROUPED FREQUENCY DIST TABLES

Question 1

When is it unreasonable to list all the individual scores in a frequency distribution table?

Answer 1

When a set of data covers a wide range of values, e.g. a set of exam scores that range from a low of X=41 to a high of X=96 (these scores cover a range of more than 50 points)

Question 2

THINK! What is a better way of organizing a wide range of scores, apart from individually?

Answer 2

Presenting them in a grouped frequency distribution table.

Question 3

What are the groups or intervals in a grouped frequency distribution table called?

Answer 3

Class intervals.

Question 4

TRUE OR FALSE: A grouped FGD should have about 10 class intervals.

Answer 4

TRUE.

10 is a general guide, but the overall idea is to have an amount of intervals that is not too few or too many so as to present a table that is relatively easy to see or understand.

Question 5

THINK! Why should the width of each interval be a relatively simple number, such as 2,5, 10, or 20?

Answer 5

Because it is easy to count by these numbers, and therefore make it easier for someone to see quickly how you have divided the range of scores.

Question 6

TRUE OR FALSE: The bottom score in each class interval should be a multiple of the width.

Answer 6

TRUE.

Question 7

TRUE OR FALSE: All intervals should be the same width.

Answer 7

TRUE.

Question 8

THINK! Consider a class interval of 40-49. What are X=40 and X=49?

Answer 8

Apparent limits (called so because they appear to form the upper and lower boundaries for the class interval)

Question 9

THINK! Consider a class interval of 50-59. What are 49.5 and 59.5?

Answer 9

The lower real limit (49.5) and the upper real limit (59.5)

Question 10

THINK! Where would two intervals, where one is 20-29 and the other is 30-39 meet? At what point?

Answer 10

They would meet at 29.5, so there are no gaps in the scale.

Question 11

TRUE OR FALSE: The width of each class interval becomes easier to understand when you consider the real limits of an interval.

Answer 11

TRUE.

For example, the interval 50-59 has real limits of 49.5 and 59.5. The distance between these two real limits (10 pts) is the width of the interval.

Question 12

TRUE OR FALSE: A class interval of 10-14 would have a width of 4 points.

Answer 12

FALSE.

It has 5 points.