Measurement and Statistics Flashcards
A set of statistics used to organize and summarize the properties of a set of data
Descriptive Statistics
A set of techniques that uses the laws of chance and probability to help researchers make decisions about what their data means and what inferences they can make from them
Inferential Statistics
A measure of what value the individual scores tend to center on
Central Tendency
The value of the most common score
Mode
The value of the middlemost score - divides a frequency distribution into halves
Median
Average score - found by adding all the scores together and dividing by the number of scores
Mean
Computation that quantifies how spread out scores of a sample are around their mean
Variance (SD^2)
Computation that captures how far, on average, each score is from the mean
Standard Deviation (SD)
How do you calculate SD?
- Subtract the mean from each Score: X-M
- Square each of the scores: (X-M)^2
- Add up the totals: Sum of (X-M)^2
- Divide the Sum by number of scores minus one
- Find the square root
(Variance is the same without step 5)
Process for studying conceptual variables?
Define the construct
Create an operational definition
Operationalize variables by recording people’s answers to questions about themselves in a questionnaire or interview
Self-Report Measures
Operationalize a variable by recording observable behaviors or physical traces of behavior
Observational Measures
Operationalize a variable by recording biological data such as brain activity, hormone levels, or heart rate
Physiological Measures
A variable whose levels are categories
Categorical (Nominal) Variable
A variable whose values can be recorded as meaningful numbers
Quantitative Variable
A Quantitative measurement scale who levels represent a ranked order in which it is unclear whether the distances are equal
Ordinal Scale
A Quantitative measurement scale that has no true zero and in which the numerals represent equal intervals between the levels
Interval Scale
A Quantitative measurement scale in which the numerals have equal intervals and the value of zero truly means nothing
Ratio Scale
An IQ test is an example of what type of scale for measurement?
Interval Scale - there is no true zero
Measuring number of times you roll a dice is an example of what type of measurement scale?
Ratio scale - you could potential count zero
How consistent the results of a measure are - same object being assessed in the same circumstance should get the same results
Reliability
The consistency in result every time a measure is used
Test-Retest Reliability
The degree to which two or more observers give consistent ratings of a set of target
Interrater Reliability
In a measure that contains several items the consistency in a pattern of answers no matter how a question is phrased
Internal Reliability
Making sure a measure measures the conceptual variable they are intended to measure
Validity of Measure
The extent to which a measure is subjectively considered a plausible operationalization of the conceptual variable in question - it looks as if it should be a good measure
Face Validity
The extent to which a measure captures all parts of a defined construct - the measure contains all the parts that the theory says it should contain
Content Validity
Establishes the extent to which a measure is correlated with a behavior or concrete outcome that it should be related to
Criterion Validity
Establishes the extent to which a measure is associated with other measures of a theoretically similar construct
Convergent Validity
Establishes the extent to which a measure does not associate strongly with measures of other theoretically different constructs
Discriminant Validity
Relationship between Reliability and Validity
Reliability of a measure is not the same as the validity
Reliability is necessary but not sufficient for Validity
A measure can be less valid than it is reliable but it can not be more valid that it is reliable
A Single number ranging from -1.0 to 1.0 used to indicate the strength and direction of an association (how close the dots on a scatter plot are to the line drawn through them)
Correlation Coefficient
A type of measurement validity that represents the extent to which a measure is related to a concrete future outcome that it should be related to
Predictive Validity
The spread of scores (highest minus lowest)
Range
The degree to which the recorded measure for a participant on some variable differs from the true value of the variable for that participant
Measurement Error
Is the scale measuring what it is supposed to measuring - how accurate is the measure
Measure Validity
Measures the extent to which all parts of the test contribute equally to what is being measured by comparing results of one half of the test with the results from the other half
Split-Half Reliability
A correlation-based statistic that measures a scale’s internal reliability
Cronbach’s Alpha
A coefficient in statistics which measures interrater agreement for qualitative terms - degree of consistency between two raters
Cohen’s Kappa
A method for establishing criterion validity in which a researcher tests two or more groups who are known to differ on the variable of interest to ensure that they score differently on a measure of that variable
Known-groups paradigm
Participants in a research scenario are given two different versions of the same test at different times - the scores are then compared to see if it is a reliable measure
Alternate Form Reliability
