Variables: Kinds and Uses

Flashcards covering definitions and distinctions among variable types, including quantitative, qualitative, discrete, continuous, ratio, ordinal, independent, dependent, extraneous, and confounding variables.

What is a variable in research?

Any element or entity which can be measured for quantity or quality.

Into what two general types are variables classified?

Quantitative variables and Qualitative variables.

How are quantitative variables measured?

Numerically.

What are the two basic sub-types of quantitative variables?

Discrete variables and Continuous variables.

What distinguishes a discrete variable?

It is counted and can only take positive whole numbers (e.g., frequency of behavior, group size).

What distinguishes a continuous variable?

Measured in ranges, can have non-whole, positive or negative values, and includes fractions (e.g., temperature, GPA).

What is a ratio variable?

A special type of continuous variable that cannot have negative values (e.g., height, weight, distance, test scores).

How are qualitative variables measured?

By assigning values to specific categories or groups; they are also called categorical variables.

What are the two kinds of categorical (qualitative) variables?

Dichotomous variables and Nominal variables.

What is a dichotomous variable?

A qualitative variable with only two distinct categories or values (e.g., Yes/No responses).

What is a nominal variable?

A qualitative variable with more than two categories or values (e.g., hair color, marital status, blood type).

What is an ordinal variable?

A variable that has values which can be ranked or ordered, combining features of quantitative and qualitative data (e.g., rating scales like A+, A, B+ or frequency categories such as rarely, sometimes, always).

What is an independent variable?

The variable that is changed or manipulated to observe its effect on the dependent variable; regarded as the cause.

What is a dependent variable?

The variable that is measured for changes; regarded as the effect influenced by the independent variable.

In an experiment on sleep time and test scores, which is the independent variable?

Amount of time spent sleeping the night before a test.

What is an extraneous variable?

Any undesirable variable other than the independent variable that may affect the experiment’s outcome, possibly introducing error.

Why are extraneous variables important to control?

If left uncontrolled, they can confound results and threaten the validity of conclusions.

What is a confounding variable?

A special type of extraneous variable that affects both the independent and dependent variables, making it hard to determine if observed effects are due solely to the independent variable.

Give an example of a confounding variable in a study of study-hours versus exam scores.

Participants’ previous knowledge of the subject, as it influences both time spent studying and the resulting exam scores.