Statistics

Question 1

Interpolation

Answer 1

estimating a value inside the rage of the data

Question 2

Extrapolation

Answer 2

estimating a value outside the range of the data

Question 3

Variance

Answer 3

Average squared distance from the mean

Question 4

Census advantages

Answer 4

Should give competey accurate results

Question 5

Census disadvantages

Answer 5

Time consuming + expensive
Cannot be used when testing process that destroys item
Hard to process large quantity of data

Question 6

Sample advantages

Answer 6

Less time consuming + expensive than census
Less data to process than census

Question 7

Sample disadvantages

Answer 7

Data may not be as accurate as census
Sample may not be large enough to give info about small subgroups of population

Question 8

Sampling units

Answer 8

Individual units of population

Question 9

Sampling frame

Answer 9

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

Question 10

Three methods of random sampling

Answer 10

Simple random
Systematic
Stratified

Question 11

Lottery sampling

Answer 11

Drawing a set number of names from a hat

Question 12

What is systematic sampling

Answer 12

When required elements are chosen at regular intervals from an ordered list

Question 13

What is stratified sampling

Answer 13

When population is divided into mutaully exclusive strata and random sample is taken from each

Question 14

Simple random sampling advantages

Answer 14

Free of bias
Easy and cheap to implement for small population/sample
Each sampling unt has known and equal chance of being selected

Question 15

Simple random sampling disadvantages

Answer 15

Sampling frame needed
Expensive + time consuming + disruptive to implement for large populations/samples

Question 16

Systematic sampling advantages

Answer 16

Simple and quick to use
Suitable for large populations

Question 17

Systematic sampling disadvantages

Answer 17

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

Question 18

Stratified sampling advantages

Answer 18

Sample reflects population structure accuratly
Garantees proportoinal representation of groups within population

Question 19

Disadvantages of stratified sampling

Answer 19

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

Question 20

Quota sampling

Answer 20

An interviewer/researcher selects sample that reflects characteristics of whole population (put people into quota until quotas are full)

Question 21

Opportunity/convienience sampling

Answer 21

Taking sample of people what are available at time study is carried out and fit desired criteria

Question 22

Advantages of quota sampling

Answer 22

Allows small group to still be representative of population
No sampling frame needed
Quick, easy, inexpensive
Allows for easy comparison between groups and population

Question 23

Disadvantages of quota sampling

Answer 23

Non-random sampling can introduce bias
Must divide population into groups, which can be costly and inaccurate
Increasing scope of study adds groups, which adds time + $
Non-responses are recorded as such (e.g. some demographics aren’t as well represented)

Question 24

Opportunity sampling advantages

Answer 24

Easy to carry out
No sampling frame needed
Inexpensive

Question 25

Opportunity sampling disadvantages

Answer 25

Highly dependant on individual researcher Unlikely to provide representative sample

Question 26

How to find lower quartile in discrete data

Answer 26

n/4. If this is whole number, Q1 is halfway between this an next data point. If not whole number, round up.

Question 27

How to find Q3 in discrete data

Answer 27

3/4 * n. If this is whole number, Q3 is halfway between this and next data point. If not whole number, round up