PSYC1040 Week 4

Question 1

Assessing operations: reliability and validity

Answer 1

• e.g a measure categorises people as introverts vs extroverts, but researchers find that those categorised as introverts go to more parties over a 6-month build

Question 2

Assessing operations: validity

Answer 2

• how well the states of the variable reflect the states of the construct
• e.g how well a measure measures what its supposed to measure

Question 3

Assessing operations: reliability

Answer 3

• insensitivity of the variable to states of other constructs
• roughly, the consistency of the variables state when they should be consistent
• these qualities of operations affect the overall validity and reliability of the study
• we can get evidence to help us judge validity and reliability
• for reliability, evidence is objective
• for validity, we can objectively compare one variable to another
• if a variable is deemed to validly reflect a construct then any variable associated with that one must also have some validity as an operation for that construct

Question 4

Describing variable using numbers: nominal variables

Answer 4

• counts of each state
• percentages - relative frequency

Question 5

Describing variable using numbers: interval or ratio variables

Answer 5

• counts of each state and relative frequency
• cumulative frequency and percentiles
• count or % within a range

Question 6

Central tendency and variability

Answer 6

• mean (centre)
• SD (spread)
• mode (most frequent)
• median - middle number

Question 7

Variability: range, variance

Answer 7

• range (difference between highest and lowest score)
• deviation from the mean - deviation = score -mean