Measurement process and measuring behaviour Flashcards
What is Measurement?
Measurement is the assignment of values to outcomes
What are the 3 measurement principles?
- An Outcome variable belongs to one of four levels
- The qualities of one level are also characteristic of the next level
- The higher the level, the more precise the measurement
Why are levels of measurement important?
Your IV and DV need to be defined as either four levels. Then you can determine the method by which you will measure them. Every variable studied must be operationally defined.
What are the 4 levels of measurement? Explain each
- Nominal
- Ordinal
- Interval
- Ratio
What is a discrete variable?
Values that have definite boundaries and can have nothing in between two values (number of students enrolled in a unit). All qualitative variables are discrete and are referred to as categorical variables (male and female).
What is a continuous variable?
Continuous variables can assume any value on some scale and it is always theoretically possible for two values to have something in between (eg time, weight, height)
A measure has high internal consistency reliability when
each of the items correlates with other items on the measure.
More information can increase the _____ and ______ utility of your results
Power and utility
Always consider defining your variables in ways that maximises utility of information
In terms of information, higher level measurements have what properties?
They have more information about the true outcome of interest along the info/complexity scale
While behavioural and social science deals with mostly nominal and ordinal level data, most test score yield ____ level data?
Interval (caution)
How you choose to measure an outcome defines the ______
outcomes level of measurement (eg preference for a product measured in multiple ways)
What is measurement error?
The discrepancy between the data found and the true value of measurement
What could account for measurement error?
Method error (the method, tools used)
Trait error (person themselves, the participants)
Temporary individual factors (fatigue, motivation, health)
Test administration (conditions, interaction between participant and examiner)
Luck
How can we decrease measurement error?
Increase reliability
How can we increase measurement reliability?
- Increase number of items/observations
- Eliminate ambiguity
- standardise conditions
- moderate difficulty
- minimise effects of external events
- standardise instructions
- standardise scoring
What is a correlation coefficient? Also known as Pearson correlation coefficient, Pearson’s r, the Pearson product-moment correlation coefficient (PPMCC)
The correlation coefficient is a statistical measure that calculates the strength and direction of the relationship between two variables. It provides a form of reliability.
It is represented by a number between -1 and +1
What are 4 types of reliability?
- Test-retest (measure of stability over time)
- Parallel forms (different forms of same test given to same participants)
- Interrater-Reliability (multilple raters agree in their observations of same thing)
- Internal consistency (responses at one time, focusses on consistency of items)
What are 4 types of validity?
- Face validity - extent to which items on a test appear to measure the construct
- Content validity - extent to which the content of the measure compares with the universe of content that defines the construct
- Criterion-related validity - (predictive OR concurrent) extent to which a score indicates a level of performance on an criterion against which it is compared
- construct validity - extent to which an assessment corresponds to other variables as predicted by a theory
What are two types of Criterion-related validity?
Predictive and concurrent
What are two types of construct validity?
Convergent validity and discriminant validity
What does internal validity refer to?
Internal validity refers to whether an experimental treatment / condition makes a difference or not, and whether there’s sufficient evidence to support the claim. It refers to the amount of control and accuracy in concluding that the outcome of an experiment is due to the independent variable.
What does external validity refer to?
Variables have been operationalised and defined and are representative of the population. It refers to the amount of generalisability.
What are some threats to internal validity?
- history
- maturation
- testing
- instrumentation
- statistical regression
- selection of subjects
- mortality
- experimenter bias
- demand characteristics
* Remember John Henry effect
What are some threats to external validity?
- multiple treatments interference - treatments occur simultaneously
- reactive arrangements (participants knowledge of the experiment)
- experimenter effects
- pretest sensitisation
How can we improve internal validity?
Randomly selecting individuals
randomly assigning to groups
use a control group
How can we improve external validity?
Careful adherence to good experimental process and practices
Improve the research design
random assignment
attempt to normalise testing procedures and environment as a much as possible
Validation studies
What are two types of sampling strategies?
Probability and
Non-probability sampling