Sampling Methods

Question 1

simple random sampling

Answer 1

Method: assign number then random number generator
Advantages: bias free, easy and cheap, equal chance of being chosen
Disadvantages: not suitable for big populations, sampling frame needed

Question 2

systematic sampling

Answer 2

Method: chosen at regular intervals, kth elements
Advantages: simple and quick, large population
Disadvantages: suitable only if sample frame is there, introduces bias if not random

Question 3

stratified sampling

Answer 3

Method: divided into groups, simple random then in groups, same proportion
Advantages: reflects population, proportional representation
Disadvantages: classified into strata is a must, sampling frame is needed

Question 4

quota sampling

Answer 4

Method: divided based on characteristics, actively chose people to fill quota
Advantages: small sample representative, no sampling frame needed, quick, easy cheap
Disadvantages: bias, non-responses not recorded

Question 5

opportunity sampling

Answer 5

Method: info from the people available
Advantages: easy and inexpensive
Disadvantages: not representative, dependent on researcher

Question 6

population

Answer 6

whole set of items of interest

Question 7

sample

Answer 7

subset of the population, representative

Question 8

sample unit

Answer 8

sampled individuals

Question 9

sample frame

Answer 9

units individually named to form a list

Question 10

census

Answer 10

information from the entire population
Advantages: accurate
Disadvantages: time consuming, cannot be done when testing involves destruction

Question 11

cluster sampling

Answer 11

sampling a few subgroups

Question 12

self-selected sampling

Answer 12

open to be sampled

Question 13

measure of central tendency

Answer 13

centre of data (mean, mode, median)

Question 14

standard deviation

Answer 14

distance from the mean, spread of data

Question 15

variance

Answer 15

standard deviation squared

Question 16

outliers

Answer 16

extreme values, (1.5 x IQR) +/- UQ/LQ

Question 17

causal relationship

Answer 17

variable directly causes change in the other, correlation does not mean causation

Question 18

regression

Answer 18

creating a model to explain the data

Question 19

interpolation

Answer 19

estimating inside the range

Question 20

extrapolation

Answer 20

estimating outside the range

Question 21

midrange

Answer 21

(lowest + highest) / 2