Descriptive statistics

Question 1

What are descriptive statistics?

Answer 1

Techniques for describing patterns in data without statistically analysing the patterns to see if they have significance.

Question 2

What are the measures of central tendency?

Answer 2

Mean, median, mode

Question 3

How is the mean calculated?

Answer 3

Adding up all the individual values and diving the total by the number of values in the data set

Question 4

How is the mode calculated?

Answer 4

The most frequently occurring value in the data set

Question 5

How is the median calculated?

Answer 5

Arranging the values in order from lowest to highest and finding the middle value

Question 6

What measure of central tendency is most sensitive?

Answer 6

Mean

Question 7

What measure of central tendency is the least sensitive?

Answer 7

Mode

Question 8

What do measures of dispersion show?

Answer 8

How ‘spread out’ the values are in a set of data

Question 9

What are the measures of dispersion?

Answer 9

Standard deviation and the range

Question 10

What is the range?

Answer 10

The difference between the highest and the lowest value in the data set

Question 11

How do you work out the range?

Answer 11

Subtract the lowest value from the highest value then add 1

Question 12

What is the standard deviation?

Answer 12

The average distance each value in the data set is from the mean

Question 13

What are the strengths and limitations of the mean?

Answer 13

STRENGTH: Most sensitive measure of central tendency as it uses all of the data - more representative of the data as a whole

LIMITATIONS: Can be distorted by extreme values

Question 14

What are the strengths and limitations of the median?

Answer 14

Strength: not affected by extreme values
Easy to calculate

Limitations: less sensitive than the mean, not all scores are included

Question 15

What are the strengths and limitations of the mode?

Answer 15

Strength: easy to calculate

Limitation: Not usually representative of the data as a whole

Question 16

What are the strengths and limitations of the range?

Answer 16

Strengths: easy to calculate

Limitations: Can be distorted by outliers

May not be representative of the data as a whole (only takes into account the two extreme values)

Question 17

What are the strengths and limitations of standard deviations?

Answer 17

Strengths: Takes into account all of the data and uses the mean in its calculation
Gives us useful information that takes us beyond the mean

Limitations: The standard deviation may be distorted if the mean has been skewed by outliers