Stats Terminology Flashcards
Causal Relationship
A relationship in which one factor can be said to be the cause of another. This relationship can be tested with controlled experiments.
Confounding Variable
A variable that is not accounted for in the experimental design, varies systematically with the dependent variable, and prevents a clear interpretation of the effect of the independent variable on the dependent variable.
Controlled, Randomized Experiment
The most powerful experimental design because it allows for the inference of causation. The participants are randomly chosen from a population and randomly assigned to one of two (or more) groups, usually an experimental group that receives some treatment and a control group that receives a placebo.
Correlation
The degree of relationship between two variables.
Cross Sectional Study
A research study that involves a single observation (such as an interview or questionnaire), which may be useful to determine how variables affect each other at the same time and period.
Degrees of Freedom
A parameter that is equal to the number of observations or groups in a study minus some value(s) that limit the observations’ or groups’ freedom to vary.
Dependent Variable
In an experiment, a measure expected to vary across different levels of the independent variable. It is also called the response variable.
Directional Alternative Hypothesis
Where the alternative hypothesis is specifically stated beforehand; for example, Group 1’s mean is greater than Group 2’s mean. This is also called a one-tailed test of significance.
Double-Blind Experiment
Neither the participant nor the treatment allocator knows whether the participant has been allocated to a treatment or control group.
Experimental Study
A type of study in which all variable measurements and manipulations are under research control. The goal of an experiment is to control the environment in such a way that manipulation of the independent variable yields a direct, corresponding change in the dependent variable.
Independent t-test
A statistical test to determine whether there are significant differences between two independent groups’ means being tested on the same dependent variable.
Independent Variable
In an experiment, the variable that the experimenter manipulated. It may also be called the treatment variable.
Mean
The arithmetical average of a group of scores
Median
The center of a distribution of score, such that half of the scores are above that number and half of the score in the distribution are below that number.
Mode
The most frequently occurring score