Psychological measurement
22 important questions on Psychological measurement
How can psychological measurement be defined?
as a process through which numbers are assigned to represent the quantities of psychological attributes, or the extend to which an attribute is present.
When does the measurement process succeed?
if the numbers assigned to an attribute reflect the actual amounts of that attribute.
What are the properties of numbers?
- Identity
- order
- quantity
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Describe the numerical property of identity.
Which rules must be followed when sorting people into categories?
the people within a category must satisfy the property of identity of the category
the categories must be mutually exclusive., person can't be in two categories at the same time
the categories must be exhaustive, the categories must cover 100% of the variation of the trait.
Describe the numerical property of order.
- they convey information about the relative amount of an attribute that people possess.
- the numbers serve again as a label, and tells us which person has the most of an attribute, not how much.
- If one person is assigned 1, then this person has less of the attribute than the person assigned 2, but how much is not known.
Describe the property of quantity.
- when numerals
have the property of quantity, they provide information about the magnitude of differences between people. - so here when someone has 15 this means that he has twice as less of the trait than someone with 30.
According to campbell, what does it take for something to be measurement?
- each object is represented by a single number (this rock weights .....)
- the sum of two assigned numbers represents the empirical combination of the two objects. (two rocks together weight .....)
- measurement requires concatenation
What is a concatenation?
What is measurement according to the representation theory of measurement?
What is a concatenation operation?
a balance scale is a tool for a concatenation operation
What is the positive manifold?
Why are psychological measurements still measurements?
- Measurement is the assigning of numerical values according to rules
- which rules doesn't matter
- determine order, determine equality, are all rules that don't follow quantitative scales but are scales of measurement.
Describe an interval level of measurement
Describe an ordinal level of measurement
Describe a nominal level of measurement.
Describe a ratio scale of measurement.
What determines the scale level of measurement?
e.g. If you assign males 54 and females 34 it would work just as well as 0 and 1
How do you know that a scale is an ordinal scale?
How do you know that a scale is an interval scale?
What is steven's statement about statistics?
- what kinds of tests you can do with data depends on what transformations you can put the data through
- Parametric tests such as t-test and ANOVA are sensitive to tranformations that change distances between scale points
- As a result, nonlinear transformations (squares) will change one’s conclusions
What is the difference between an interval scale measurement and a ratio level measurement?
- Ratio has additivity and multiplitivity, so there 80 meters is twice as much as 40 meters, but 80 degrees celsius isn't twice as much as 40 degrees celsius
- zero; with interval scales, 0 doesn't mean no heat. But with ratio scales 0 does mean no distance.
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