Statistics- As

Question 1

Define population

Answer 1

whole set of items of interest

Question 2

Define sample

Answer 2

some subset of the population intended to represent the population

Question 3

Define sampling unit

Answer 3

one item from population

Question 4

Define sampling frame

Answer 4

List of members of a population

Question 5

Advantages and disadvantages of a census

Answer 5

Adv- gives a completely accurate result

Dis- Time consuming and expensive
Cannot use for destruction
Lots of data to process

Question 6

Advantages and disadvantages of taking a sample

Answer 6

Adv- Easy and cheap
can be used with destruction
Less data to process

Dis- Less representative of the population
May not be large enough to represent
some subgroups

Question 7

Define census

Answer 7

Data taken from the entire population

Question 8

How to increase the accuracy of a sample

Answer 8

Increase sample size

Question 9

How to carry out a simple random sample

Answer 9

Give all in the sampling frame a number

Use a random number generator to generate enough number for a sample

The numbers generated select the sample

Question 10

Advantages and disadvantages simple random sample

Answer 10

Adv- Free of bias
Easy and cheap
equal chances of selection for all

Dis- Not suitable for large populations,
sampling frame is needed

Question 11

How to carry out a systematic sample

Answer 11

Take Kth elements at regular intervals

K= Population size/ sample size

Start at a random number between 1 and k

Question 12

Advantages and disadvantages of a systematic sample

Answer 12

Adv- Simple and quick
Suitable for large samples

Dis- Sampling frame is needed
Can introduce bias of sampling frame
as not random

Question 13

How to carry out stratified sampling

Answer 13

Divide the population in to different strata

Simple random sample within strata

Choose number form sample in proportion to population use formula
Sample size/ sample size

Question 14

Advantages and disadvantages of stratified sampling

Answer 14

Adv- Reflects the population structure
Guarantees proportional
representation of the population

Dis- Population must be clearly classified
into strata
Each strata needs a sampling frame

Question 15

How to carry out a quota sample

Answer 15

Divide the population into groups

Quota is set out and selected to reflect the proportions in the population

Interviewer selects the sample units

Question 16

How to carry out an opportunity sample

Answer 16

Sample is taken form the people available to the interviewer at the time of study who meets criteria

Question 17

Advantages and disadvantages of opportunity sampling

Answer 17

Adv- easy to carry out
Inexpensive

Dis- Unlikely to provide a representative
sample
Highly dependent on individual
researcher

Question 18

Advantages and disadvantages of quota sampling

Answer 18

Adv- Allows small sample to be
representative
No sampling frame needed
Quick and easy and cheap

Dis- Introduces bias
Population must be divided into groups
Non responses are not recorded

Question 19

Define qualitative data

Answer 19

Non numerical values e.g. colour

Question 20

Define Quantitative data

Answer 20

numerical values

Question 21

2 types of quantitative data and define

Answer 21

Discrete- can only take specific values e.g. shoe size

Continuous- Can take a range of values, such as decimal e.g. height in metres

Question 22

What happens when you group data

Answer 22

you loose the original values

Question 23

Two criteria to cover when comparing two data sets

Answer 23

Use a measure of spread and a measure of location

Question 24

Measures of location

Answer 24

Minimum/maximum values

Quartiles/ percentiles/ deciles

Central tendency- mean mode median

Question 25

Measures of spread

Answer 25

Range IQR Standard deviation / variance

Question 26

Formal to work out the median of a grouped data set

Answer 26

class start+ class width x frequency into class/ class frequency

Question 27

Median value for listed data

Answer 27

n/2 Round up if a decimal value is calculated If a whole number then take halfway between that number and the next

Question 28

What are Q1 and Q3

Answer 28

The lower and upper quartiles

Question 29

What is variance

Answer 29

The average squared distance from the mean

Question 30

What is standard deviation

Answer 30

Average distance form the mean The square root of the variance

Question 31

How to calculate variance

Answer 31

msmsm Mean of the squares minus the squares of the mean

Question 32

what is bivariate data

Answer 32

data with two variables

Question 34

Key word when describing correlation to avoid hinting to causation

Answer 34

tends to

Question 35

What is a regression line

Answer 35

line of best fit but for a scatter graph