GRAVETTER_CH02_PERCENTILES, PERCENTILE RANKS, AND INTERPOLATION

Question 1

TRUE OR FALSE: The sole purpose of a frequency distribution is to provide a description of an entire set of scores.

Answer 1

FALSE.

It can also be used to describe the position of an individual within the set.

Question 2

What is the term for individual scores or x values?

Answer 2

Raw scores

Question 3

What is the term for the percentage of individuals in the distribution with scores at or below the particular value?

Answer 3

Rank or percentile rank

Question 4

When a score is identified by its percentile rank, the score is called a ___________.

Answer 4

percentile

Question 5

TRUE OR FALSE: The percentile rank refers to a percentage, while the percentile refers to a score.

Answer 5

TRUE.

e.g. X=43 has a percentile rank of 60% and the score would be called the 60th percentile.

Question 6

What are the values that result from counting the number of scores that are in or below each category on a scale, and represent the accumulation of individuals as you move up the scale?

Answer 6

Cumulative frequencies (cf)

Refer to Ex 2.6, p.50

Question 7

The percentage of individuals with scores at or below a particular point in the distribution. These are associated with the upper real limits of the corresponding scores or intervals.

Answer 7

cumulative percentages (c%)

Question 8

THINK! What is the relationship between cumulative frequencies (cf) and upper real limits?

Answer 8

The key is to remember that the values in a frequency distribution table are usually measurements of a continuous variable, therefore real limits exist. When considering cumulative frequencies, we must always recall that these values represent intervals on a scale of measurement.

Question 9

This is a process used to estimate values within intervals of two different scales by assuming that fractional portions of one scale correspond to the same fractional portions of the other scale.

Answer 9

Interpolation

Question 10

TRUE OR FALSE: A basic assumption underlying interpolation is that there is a constant rate of change from one end of the interval to the other.

Answer 10

TRUE.

It is because of this assumption that the values we calculate through interpolation are only estimates.