Variables Flashcards
Define:
-Variable
-Independent variable
-Dependant variable
Variable:
An event, object or behaviour that has at least two values and can be measured
Independent variable:
The condition being manipulated by the experimenter to determine it’s effect on an outcomes
Dependent variable:
Measurement of behaviour that reflects the effect of the independent variable
What is the nature of variables, independent variables and dependant variables?
VARIABLES
Can be MANIPULATED(establish cause and effect)
or OBSERVED (non-experimental)
The Independent variable is manipulated to effect the dependent variable which is measured.
Define:
-Covariant variable
-Confounding variable
What is the nature of covariant and confounding variables
Covariant variable:
A controlled for independent variable or unwanted confounder
Confounding variable:
A variable unaccounted for.
Covariant variables are controlled for third (independant) variables that when not controlled become confounding variables - unaccounted for & unwanted variables.
Covariant can be confounding or not.
All confounding’s are covariant
Define and explain:
- Correlation
- Cause and effect
CORRELATION:
Measurment of the linear relationship between variable x and y
Observable not manipulated
Observation often does not allow for cause and effect
Positive, negative, no correlation, spurious correlations (need more data).
CAUSE AND EFFECT:
Established using experiemntal manipulation (Independant manipulated to effect dependant)
Can be established within subjects or between groups
Define:
-Operationalization:
-NOIR
Operationalization:
-How clearly a variable is defined by the researcher
-We need to obtain an objective measure of both our independent variables and dependent variables; we must operationalize them.
NOIR
The four different scales variables are measured on
Define and explain:
- Nominal scale
- Ordinal scale
Nominal scale:
-Deals with relations, classes and frequencies (one or the other) smoker or non-smoker
-Nominal variables cannot be added, subtracted, multiplied or divided (they are numbers).
Ordinal scale:
-When numbers rank, not the distance between scores (questionnaire)
-e.g., 1: strongly agree; 2: agree; 3: neutral; 4: disagree; 5: strongly disagree.
-Ordinal variables cannot be added, subtracted, multiplied or divided.
Define and explain:
- Interval scale
- Ratio scale
Interval scale:
Numbers rank and reflect distance between scores with no zero (temperature)
-Interval measurements are continuous and zero is arbitrary - e.g. temperature. “20c is warmers than 10c”
-Interval variables can be added or subtracted, but it is not meaningful to multiply or divide them
Ratio scale:
-Numbers reflect rank and distance between scores
-Zero is absolute. e.g., income, height, weight
-For example, number of correct answers of a multiple choice test
-“Continuous, zero is zero, makes sense, if you are 50kg you are 50kg
Interval and ratio scales can be continuous (“3.25 years of age”) or discrete (no fractions – e.g. can’t have 2.23 children)
Define and explain:
-Validity
-Face validity
-Internal validity
-External validity
-Construct validity
Validity:
When a test measures it’s intended measurement.
Face validity: does it look like we are measuring the right thing? “Common sense”
Internal validity: the change in the dependent variable occurs because we change the independent variable. “How we see the workings of the internal experiment”
External validity: extent to which the result applies in the real world. “does it translate from the lab to the real world”
Construct validity: Does your test measure the concept being studied?
Define and explain:
-Reliability
-Test-retest reliability
-Split-half reliability
Reliability: does a test provides a repeatable measure?
Test-retest reliability: if the same person does the test twice, are the results similar both times?
Split-half reliability: Does the score from one half of the test give a similar result to the score from the other half?
