Statistics Flashcards Preview

Edexcel A Level Maths > Statistics > Flashcards

Flashcards in Statistics Deck (23)
Loading flashcards...
1

Population

A set of items that are of interest

2

Census

Measures every member of a population

3

Sampling unit

A selection of the population used to estimate information about the population as a whole

4

Sample

A selection of the population used to estimate information about the population as a whole

5

Simple random sampling

Every element in the set has an equal chance of being selected

6

Systematic sampling

Members are chosen at regular intervals from an ordered list

7

Stratified sampling

The population is divided into groups e.g. male and female. The proportions should reflect the proportions of the population as a whole

8

Advantages of simple random sampling

Free of bias
Easy and cheap
Equal chance of selection

9

Disadvantage of simple random sampling

Not suitable for a large population or sample size

10

Advantages of systematic sampling

Simple and quick to use
Suitable for large samples and populations

11

Disadvantages of systematic sampling

A sampling frame is needed
Possible bias because there is not an equal chance of selection

12

Advantages of stratified sampling

Accurately reflects the population
Guarantees proportional representation of groups

13

Disadvantages of stratified sampling

Can be time consuming

14

Quota sampling

Similar to stratified
A researcher will select a sample that reflects the characteristics of the group

15

Opportunity sampling

The sample is taken from people available at the time and who fit the criteria needed
Like random

16

Quantitative data

Numerical data (eg hight)

17

Discrete data

Data which can only take certain values (eg only an integer)

18

Qualitative data

Non numerical data (eg colour, or worded answers)

19

Continuous data

Data that can take any value (eg height, length)

20

How do you tell that there isn’t a skew

Mean = median = mode

21

How do you tell that there is a positive skew

Mean > median > mode

22

How do you tell that there is a negative skew

Mean < median < mode

23

What is variance

Standard deviation squared