Statistics

Question 1

What is a sample

Answer 1

Some subset of the population intended to represent the population

Question 2

What is a sampling unit

Answer 2

Each individual in the population that can be sampled

Question 3

What is a sampling frame

Answer 3

Numbered or named to form a list

Question 4

Advantages of using a census

Answer 4

Should give completely accurate result.

Question 5

Disadvantages of using a census

Answer 5

Time consuming and expensive.
Can not be used when testing involves destruction.
Large volume of data to process.

Question 6

Advantages of using a sample

Answer 6

Cheaper
Quicker
Less data to process

Question 7

Disadvantages of using a sample

Answer 7

Data may not be accurate.
Data may not be large enough to represent small sub-groups.

Question 8

How to carry out simple random sampling

Answer 8

In sampling frame each item has identifying number. Use random number generator, or ‘lottery sampling’ (names in a hat

Question 9

What is simple random sampling

Answer 9

Every sample has an equal chance of being selected

Question 10

Advantages of simple random sampling

Answer 10

Avoids bias
Easy and cheap to implement
Each nu. Has an equal chance

Question 11

Disadvantages of random sampling

Answer 11

Not suitable when population size is large
Sampling frame is needed

Question 12

How to carry out systematic sampling

Answer 12

Elements chosen at regular intervals

Question 13

Advantages of systematic sampling

Answer 13

Simple
Quick
Suitable for larger samples / populations

Question 14

Disadvantages of systematic sampling

Answer 14

Sampling frame needed
Can introduce bias is sampling frame is not random

Question 15

When is stratified sampling used

Answer 15

Used when sample is large + pop. Naturally divides into two groups

Question 16

How to carry out stratified sampling

Answer 16

Population divided into groups (strata) and a simple random sample carried out in each group.

Same proportion (𝑠𝑎𝑚𝑝 𝑠𝑖𝑧𝑒 (𝑛))/(𝑝𝑜𝑝 𝑠𝑖𝑧𝑒 (𝑁) ) sampled from each strata.

Used when sample is large and population naturally divides into groups.

Question 17

Advantages of stratified sampling

Answer 17

Reflect population structure

Guarantees proportion representation of groups within the population

Question 18

Disadvantages of stratified sampling

Answer 18

Population must be clearly classified into distinct strata.
Selection within each stratum suffers from same disadvantages as simple random sampling.

Question 19

How to carry out quota sampling

Answer 19

Population divided into groups according to characteristic. A quota of items/people in each group is set to try and reflect the group’s proportion in the whole population. Interviewer selects the actual sampling units.

Question 20

Advantages of quota sampling

Answer 20

Allows small sample to still be representative of population.
No sampling frame required.
Quick, easy, inexpensive.
Allows for easy comparison between different groups in population

Question 21

Disadvantages of quota sampling

Answer 21

Non-random sampling can introduce bias.
Population must be divided into groups, which can be costly or inaccurate.
Increasing scope of study increases number of groups, adding time/expense.
Non-responses are not recorded.

Question 22

How to carry out opportunity sampling

Answer 22

Sample taken from people who are available at the time of study, and who meet the criteria

Question 23

Advantages of opportunity sampling

Answer 23

East to carry out
Inexpensive

Question 24

Disadvantages of opportunity sampling

Answer 24

Unlikely to provide a representative sample

High dependent on individual researcher

Question 25

What is range + how to calculate e

Answer 25

It’s a measure of variation Highest - lowest value

Question 26

What are percentiles

Answer 26

Divide data in 10 Eg. Q1 = 25th percentile

Question 27

How to find a interpercentile range

Answer 27

Subtracted 2 percentiles

Question 28

How to find the mean

Answer 28

Total ——- How many Or EX — n

Question 29

How to find mean from a table

Answer 29

Mid point x frequency —————————— n

Question 30

What is the median

Answer 30

Middle data value when all the data values are placed in order of size

Question 31

What is the mode

Answer 31

Most frequently occurring data value

Question 32

Definition of an outlier

Answer 32

An observation that lies outside the overall pattern of distribution

Question 33

Give a reason to support the use of histograms to represent this data

Answer 33

……. Is continuous Grouped

Question 34

What are the features of a histogram

Answer 34

No spaces between bars Area is proportional to frequency

Question 35

frequency density equation

Answer 35

FD = F / CW

Question 36

What does area = on a histogram

Answer 36

Area = K x frequency

Question 37

Statistical distributions What’s does X mean

Answer 37

A random variable (It doesn’t have a fixed value)

Question 38

Statistical distributions What does x mean

Answer 38

A particular value X can take

Question 39

What is a descrete random variable

Answer 39

Only have a certain number of possible values

Question 40

What do all probabilities add ot

Answer 40

1

Question 41

How do you tell which is the mode In terms of probability

Answer 41

the value with the biggest probability

Question 42

Statistical distributions What is the binomial coefficient equation

Answer 42

(n) n n! = C = ———- (r) r r! (n-r)!

Question 43

Probability What does n mean

Answer 43

2 shaped areas

Question 44

Probability What does u mean

Answer 44

1 or 2 shaded areas

Question 45

What does mutant exclusive mean

Answer 45

No overlap

Question 46

What is the mutatly exclusive equation

Answer 46

P(AuB) = p(A) + p(B)

Question 47

What does independent eventsmean

Answer 47

No effect on each other

Question 48

Independent events equations

Answer 48

p(AnB) = P(A) x P(B)

Question 49

What is the formula of the regression line

Answer 49

Y = a + bx

Question 50

What is interpolation Is it reliable

Answer 50

Values of x within the data range It’s reliable

Question 51

What is extrapolation Is it reliable

Answer 51

Use of values of x outside the data range It’s unreliable

Question 52

What variable do you put on the xaxis

Answer 52

Independent

Question 53

What value do you put on the y axis

Answer 53

Dependent

Question 54

What is a hypothesis

Answer 54

A statement made about the value of a population parameter that we wish to test by collecting evidence in the form of a sample

Question 55

What is a null hypothesis

Answer 55

The default

Question 56

What is an alternative hypothesis

Answer 56

That there has been some change in the population parameter

Question 57

What is a test statistic

Answer 57

The evidence from the sample

Question 58

What is the level of significance

Answer 58

Is the maximum probability where we would reject the null hypothesis

Question 59

What is the critical region

Answer 59

The range of values f the test statistic that would lead to you rejecting H0

Question 60

What is the actual significance level

Answer 60

The actual probability of being in the critical region