Scaling L1.2 Flashcards
1
Q
What is psychological measurement?
A
- Psychological measurement is a process through which numbers are assigned to represent the quantities of psychological attributes.
- Psychologists believe that if something exists then it must be quantifiable.
- This is true even if it is not directly observable.
2
Q
What is scaling?
A
Scaling concerns the way in which numerical values are assigned to psychological attributes.
3
Q
What are used to represent an individual’s level of a psychological attribute.
A
Numerals
4
Q
What are the 3 key properties in psychological measurement?
A
1) Property of identity
2) Property of order
3) Property of quantity
5
Q
Properties of identity
A
- simplest measurement
- categorise people who share a psychological feature.
- Teachers can categorise their students into “behavioural problems” vs. “no behavioural problems.”
- There are rules to sorting behaviours into categories
6
Q
What are the rules to sorting behaviours into categories?
A
- The categories must be mutually exclusive. - (an introvert can not also be an extrovert)
- The categories should be exhaustive -(do all children fit neatly into “behavioural problems” vs. “no behavioural problems”?
- maybe another category would be needed for something in the middle.) - All people classified within a given category must be identical with respect to the attribute interest. -(are all children with the behaviour problem category the same? Some might be physically aggressive toward others, whereas others simply talk too much.)
7
Q
Properties of Order
A
- Provides more information than the property of identity
- Ranking is a prototypical example of the property of order.
- E.g. A teacher may be asked to rank all of the students with respect to their interest in learning.
8
Q
Properties of Quantity
A
- The property of quantity provides more information than the property of order.
- The property of quantity reflects the ability of numerals to provide information about the magnitude of differences between people.
- E.g., if person A has a brain weight of 1084 grams and person B has a brain weight of 1254 grams, we can say that person B has a brain 15.7% larger than person A.
9
Q
What is additivity?
A
- Additivity implies that the size of a measurement does not change as the units are being counted.
- Whether you add 1 unit going from 105 to 106 or from 1 to 2, that one unit increase represents the same amount.
- Thus additivity requires unit size to remain constant.
10
Q
What is conjoint measurement?
A
When additivity is perfectly satisfied.
11
Q
Define measurement
A
The assignment of numerals to objects or events according to rules.
12
Q
What are the 4 scales or levels of measurement?
A
1) Nominal
2) ordinal
3) interval
4) ratio
12
Q
Nominal Scales
A
- It is the most fundamental level of measurement
- “Symbols or numerals that have a property of identity are used to label observations in which behaviours have been sorted into categories according to some psychological attribute.”
- identifies all people associated with that label to possess a unique feature or attribute in common.
- E.g. Gender: male and female, which state you live in is a good example
- There’s no obvious or meaningful order which you could place states.
- But are these examples psychological variables or attributes?
13
Q
Ordinal Scales
A
- “The ordinal scale links observations of behaviour thought to reflect qualitative differences in amounts of an attribute to symbols or numerals that have the property of order.”
- The key difference in comparison to the nominal scale is that there is an ordering in the attribute of interest.
- Ranks are often provided as an example of an ordinal scale.
14
Q
Interval scales
A
- Interval scales are more informative than ordinal scales.
- With interval scales there is a constant distance between each of the units.
- However there is no meaningful zero point in interval scales.
- Thus you can say that the difference between 15 and 30 degrees Celsius is equal to the difference between 30 and 45 degrees Celsius.
- However you can’t say that 45 degrees Celsius has 50% more warmth than 30 degrees Celsius
- 0 Celsius does not indicate the absence of heat.
- The absence of a meaningful 0 point prevents the multiplication or division of values.
