Descriptive Statistics

Question 1

Define mean

Answer 1

An arithmetic average if a set of scores calculated by dividing the sum of scores by the number of scores.

Question 1

Define measures of central tendency

Answer 1

A central or typical value of set values/findings an average.

Question 2

What are the strengths of mean

Answer 2

It takes all scores into account so is the most sensitive measure.

Question 3

What are the limitations of mean

Answer 3

Easily distorted by extreme scores, making it unrepresentative. The median might be more representative in this case.
Can give a peculiar measure that cannot represent reality e.g. a mean could be 2.6 children when that is not possible.

Question 4

Define median

Answer 4

The middle values of a set of scores.

Question 5

What are the strengths of median?

Answer 5

More representative than the mean, especially with small data sets.
Unaffected by extreme scores in one direction e.g. one extremely high or one extremely low score.

Question 6

What are the limitations of median?

Answer 6

Less representative when the data set is polarised e.g. has both one extremely high and one extremely low score.

Question 7

Define mode

Answer 7

The most frequently occurring value in a set of scores.

Question 8

What are the strengths of mode?

Answer 8

Unaffected by extreme scores.
Most useful with a large data set.

Question 9

What are the limitations of mode?

Answer 9

Unreliable for use with small data sets as small changes to scores can result in it being multimodal e.g. there being more than one mode.

Question 10

Define measures of dispersion

Answer 10

Values which give an indication of how spread out a set of scores are.

Question 11

Define range

Answer 11

A measure of dispersion that is the difference between the highest and lowest score in a data set.

Question 12

What are the strengths of range?

Answer 12

Easy to calculate and give an indication.
Useful when the median is being used as an average as the range uses the top and bottom of a set and the median is the middle number.

Question 13

What are the limitations of range?

Answer 13

Easily distorted by extreme scores.
Only uses two numbers from a data set no matter how large the data set is so is a basic indicator of spread at best.
It gives not indication of the spread of scores within a data set.

Question 14

Define standard deviation

Answer 14

Measure of dispersion that shows how much each score in the data set deviates on average from the mean of that data set.

Question 15

What are the strengths of standard deviation?

Answer 15

Uses all scores in a data set in its calculation.
It gives a sensitive measure of how all scores are dispersed around the mean.
It is a powerful statistics with applications elsewhere e.g. in conjunction with normal distributions.

Question 16

What are the limitations of standard deviation?

Answer 16

More difficult to calculate than the range. As it uses the mean, it can be distorted by extreme scores.