Competency: Differentiates kinds of variables and their uses, designs a research useful in daily life and writes a research title, and describes background of research and states research questions.

What is Variable?

A variable is a variation within class of objects (i.e., eye color). A constant is a characteristic with no variations within a class of objects (i.e., grade level of ninth graders). Researchers choose certain variables to study since they are suspected to be related to a possible relationship to be discovered.

Quantitative vs. Categorical Variables

Variables are classified as either quantitative or categorical. A quantitative variable is conceptualized and analyzed in distant categories, with no continuum implied (i.e., height—this can be subdivided into smaller units).

A categorical variable does not vary in degree, amount, or quantity, but are qualitatively different (i.e., political party – there is no middle ground or in-between measurement).

Other Types of Variables

Outcome Variable

• A dependent variable that is quantitative

• Most studies demonstrating this would have a categorical independent variable

• The investigator is interested in the effects that might lead to differences in methods = outcomes.

• This usually illustrated using diamond shape.

Moderator Variable

• Special type of independent variable

• Selected to determine if it affects (modifies) the basic relationship between the primary independent variable and the dependent variable.

What is Hypothesis?

A hypothesis (plural- hypotheses) is a precise, testable statement of what the researcher(s) predict will be the outcome of the study.

This usually involves proposing a possible relationship between two variables: the independent variable (what the researcher changes) and the dependent variable (what the research measures).

In research, there is a convention that the hypothesis is written in two forms, the null hypothesis, and the alternative hypothesis (called the experimental hypothesis when the method of investigation is an experiment.

Alternative Hypothesis (H_i)

This states that there is a relationship between the two variables being studied (one variable has an effect on the other).

It states that the results are not due to chance and that they are significant in terms of supporting the theory being investigated.

Null Hypothesis (H_o)

The null hypothesis states that there is no relationship between the two variables being studied (one variable does not affect the other).

It states results are due to change and are not significant in terms of supporting the idea being investigated.

Can a hypothesis be proven?

Upon analysis of the results, an alternative hypothesis can be rejected or accepted, but it can never be proven to be correct.

We must avoid any reference to results proving a theory as this implies 100% certainty, and there is always a chance that evidence may exist which could refute a theory.

How to Write a Hypothesis?

1. To write the alternative and null hypotheses for an investigation, you need to identify the key variables in the study. The independent variable is manipulated by the researcher and the dependent variable is the outcome which is measured.

2. Write your hypothesis. A good hypothesis is short (i.e. concise) and comprises clear and simple language).