# Statistics Flashcards Preview

## A-Level Maths Edexcel > Statistics > Flashcards

Flashcards in Statistics Deck (17)
1
Q

Standard Deviation

A

o = √Ex^2/n - mean^2

2
Q

Census

A

Observing or measuring every member of the population

3
Q

Population

A

the whole set of items that are of interest

4
Q

Sample

A

A selection of observations taken from a subset of the population that are used to find out information about the population as a whole

5
Q

A

Gives completely accurate results

6
Q

A
• Time consuming and expensive
• Cannot be used when the testing process destroys the item
• Hard to process large quantity of data
7
Q

A
• Less time consuming and expensive than a census
• Fewer people have to respond
• Less data to process than a census
8
Q

A
• The data will not be as accurate
• The sample may not be large enough to give information
9
Q

Sampling units

A

Individual units of a population

10
Q

Sampling frame

A

When sampling units are individually named or numbered to form a list

11
Q

Three methods of random sampling:

A
1. simple random sampling
2. systematic sampling
3. stratified sampling
12
Q

Simple random sampling

A

Every sample of size n has equal chance of being selected

13
Q

Systematic sampling

A

The required elements are chosen at random intervals from an ordered list

14
Q

Stratified sampling

A

The population is divided into mutually exclusive strata (e.g. males and females) and a random sample is taken from each

15
Q

Two methods of non-random sampling:

A
1. Quota sampling
2. Opportunity sampling
16
Q

Quota sampling

A

An interviewer or researcher selects a sample that reflects the characteristics of the whole population

17
Q

Opportunity sampling

A

Taking the sample from people who are available at the time of the study and who fit the criteria they are looking for