Statistics

Question 1

Census

Answer 1

Census observes or measures every member of a population

Question 2

Sample

Answer 2

Sample is a selection of observations taken from a subset of population to find out info about population as a whole

Question 3

Adv and dis adv of census

Answer 3

Adv
Should give a completely accurate result
Dis
Time consuming a d expensive
Cannot be used when testing destroys item
Hard to process large quantities

Question 4

Sample adv

Answer 4

Adv
Less time consuming and expensive than census
Fewer people have to respond
Less data to process

Question 5

Sample dis adv

Answer 5

Data may not be as accurate

Sample may not be large enough to give info about population

Question 6

How does size of sample affect validity of conclusions drawn

Answer 6

Size of sample depends on required accuracy and variable.
Larger sample, greater accuracy
If population is varied, you need a larger sample than if population was uniform

Question 7

Sampling units

Answer 7

Sampling units are individual units of a population

Question 8

Sampling frame

Answer 8

Sampling frame is when sampling units of population are individually named/numbered to form a list

Question 9

Describe random sampling

Answer 9

Random sampling is when every member of population has an equal chance of being selected. Sample should be representative of population. Random sampling also helps to remove bias

Question 10

What are 3 types of random sampling

Answer 10

Simple random sampling
Systematic sampling
Stratified sampling

Question 11

Describe simple random sampling

Answer 11

Sampling frame is made and each person is allocated a number and the numbers are selected through calculator/computer or lottery sampling

Question 12

Lottery sampling

Answer 12

Lottery sampling is when members of sampling frame names are written on tickets and placed into hat. Hat is shaken

Question 13

Systematic sampling

Answer 13

Systematic sampling is when required elements are chosen at regular intervals from an ordered list. E.g if sample size 20 was needed, and there were 100 people, you would take every 5th person 100/20=5

Question 14

Stratified sampling

Answer 14

Stratified sampling is when population is divided into mutually exclusive strata and random sample is taken form each