Week 4 - Measurement and Sampling Methods

Question 1

explain the meaning of measurement and describe the four scales of measurement

Answer 1

Measurement- important factor in obtaining reliable, valid results.

Nominal-names to classify variables (eg: surveys on gender, eye colour etc)
Interval scale- defined ranks and intervals (equal distance apart)
Ratio scale- equal intervals with an order/rank (can include 0)
Ordinal scale- use rank or order to measure variables (Likert scale)

Question 2

explain the difference between reliability and validity, and describe the different types of reliability and validity

Answer 2

Reliability - refers to consistency or stability of measurement
Validity - refers to accuracy of measurements.

HR + LV = results consistent but don’t measure intended variable.
HR + HV = measured intended variable, consistently.
LR + LV = low reliability therefore low validity
LR + HV = this combo not possible, does not exist.

Question 3

explain the meaning of sampling and its terminology

Answer 3

The process of choosing a sample or group from a population (can be random and non-random)

Question 4

describe each of the random and non-random sampling techniques, including the sampling approaches used in qualitative research.

Answer 4

Random - selecting group at random from population, minimising bias and possibility of error (stratified or cluster random sampling)

Non-random sampling- selecting the group according to a criteria (potential for bias)

In qualitative- 
maximum variation sampling
extreme case sampling
homogenous sample selection
typical case sampling
critical case sampling
negative case sampling
opportunistic sampling