Presenting Data

Question 1

Random sample

Answer 1

Where the things being selected have an equal chance of being selected e.g. names in a hat.

Question 2

Stratified sample

Answer 2

Where the sample keeps the same proportions as the total population e.g. if 25% of of the pupils in a school are girls, the sample taken will have 25% of girls as well.

Question 3

Bar charts

Answer 3

• For discrete (specific) data.
• Frequency given by height of bars.

Question 4

Histograms

Answer 4

• For continuous data
• Data divided into (potentially uneven) data.
• Frequency given by area of bars.

Question 5

Frequency density

Answer 5

Frequency / Classwidth

Question 6

Position of the median on a table

Answer 6

n + 1 / 2

Question 7

How to compare?

Answer 7

• Must include a measure of average (mean, median, mode)
• Measure of spread (range, interquartile)
• Context - link to the question.

Question 8

Method for capture - recapture

Answer 8

1) Take a sample of the population
2) Mark each item in the sample
3) Put the times back into the population and ensure they are thoroughly mixed.
4) Take a second sample and count how many of your sample are marked
5) The proportion of marked items in your new sample should be the same as the proportion of marked items from the population in your first sample.

Question 9

How to state assumptions for capture - recapture?

Answer 9

1) Population change
2) Markings