How to Adapat a Measuring Instrument

ASSESSMENT PYC4807 - PREAMBLE

Variables

Latent variables: variables that is not directly observed but that is inferred

Manifest variables: can be directly observed

To measure latent variables we have to specify a manifest variable to measure this provides an operational definition or a measurement model for the construct. A scale may be needed to measure the variables. The reliability and validity of measures must be reported

The values of a variable can refer to the type of measurement scale they are associated with.

Measurement levels:

Nominal: discrete, mutually exclusive, exhaustive e.g. sex/gender. Numerals are assigned for classification purposes

Ordinal: items are ranked in order of importance e.g. neutral, agree, and strongly agree. The interval cannot be measured or compared. Includes characteristics for nominal scales.

Interval: the distance between the points on the ordinal scale can be measured. Includes characteristics for ordinal and nominal scales

Ratio: has an absolute zero – can measure weight, height, time etc

Mean – average - ( or mu

Median – middle values

Mode – the value that occurs the most times

Probability

Introduction to probability

- Probability is a measure of uncertainty

- Used to generalise from the sample to the population

- Involves some uncertainty

- Findings are not seen as conclusive but probable

Defining probability

- Used to help estimate the likelihood of an event happening

- Obtain the probability of an event by dividing the occurrence of the event by the total number of possible outcomes

- P (E) Number of favourable events /

Number of possible outcomes

P = probability E = event such as Aces in a deck of cards

P(ace) = no of aces / = 4/ = 1/

No of cards in a deck 52 13

- The formula is based on the assumption that all outcomes are equally...