Lecture 2 - Research Design Flashcards
Independent Variable
The variable manipulated by the experimenter; the variable that is changed.
Dependent Variable
The variable that is measured and presumed to be directly affected by the IV; the variable that changes.
Levels of Measurement
Refers to the different ways in which quantitative data can be organized and communicated: nominal, ordinal, interval, and ratio.
Between-Subjects Design
Each condition of the independent variable is experienced by only one group of participants.
Within-Subjects Design
Each participant experiences all levels of the independent variable.
One-Tailed & Two-Tailed Hypotheses
A one-tailed hypothesis is more precise and predicts the direction of an effect.
A two-tailed hypothesis is formulated when the likelihood of some difference or effect is known, but the direction of that effect is unknown.
Type I & Type II Errors
Type I errors occur when the null hypothesis is rejected, and the experimental hypothesis is incorrectly accepted (a false positive).
Type II errors occur when we incorrectly fail to reject the null hypothesis (a false negative).
Experimental Hypothesis
The hypothesis that in an experiment, the results in the experimental group will differ slightly from those in the control group, and that the difference will be caused by the independent variable.
Null Hypothesis
The hypothesis or condition that there is no effect of one variable on the other.
Discrete Data
Data in which no continuum exists; it can only take on certain units, and can be arranged in naturally occurring or arbitrarily selected groups or sets of values.
Continuous Data
Data with a potentially infinite number of possible values along a continuum; can be organized by different levels of measurement.
Nominal
The level of measurement that involves assigning scores that are category labels.
Ordinal
The level of measurement that involves assigning scores so that they represent a rank order.
Interval
The level of measurement that involves assigning scores of equal intervals where there is no absolute zero.
Ratio
The level of measurement that involves assigning scores in which differences between data can be quantified and their proportions specified; there does exist an absolute zero.
