DISPLAYING AND COMPARING DATA

Question 1

Choropleth map

Answer 1

Map or diagram using shading. Darker shading represents a higher number.

Question 2

Frequency density

Answer 2

Used for bar heights on a histogram. So bar area = frequency.

Question 3

(measure of) central tendency

Answer 3

This means average. e.g. mean, median, mode.

Question 4

(measure of) dispersion

Answer 4

This means spread. e.g. range, IQR, standard deviation, variance.

Question 5

Variance

Answer 5

Square of standard deviation.

Question 6

Interpercentile range (IPR), interdecile range

Answer 6

The range of a central part of a distribution. e.g. 10th to 90th interpercentile range is the spread of the middle 80% of data. e.g. 2nd to 8th interdecile range is the spread of the middle 60% of data. (Similar to IQR but can be used to discard less data at either end.)

Question 7

Standardised score

Answer 7

FORMULA - (Value - Mean) / Standard Deviation. Finds how many standard deviations from the mean a value is.) Formula is not given – must be learnt. Standardised scores are used to compare values from different distributions. Positive indicates above mean, negative indicates below mean. A higher standardised score may be good (eg for test scores), or bad (e.g. for race times).