A hypothesis is a suggested explanation for an observed relationship or a causal prediction about a relationship among several variables.  Every research project is based on a hypothesis, which generally begins with a specific question.  For example, “If people are provided with basic eye care services, will they be more economically productive on an individual basis?” This question is specific enough to be addressed by a research project, however it is not yet a hypothesis.  Next, the researcher must operationalize the terms being used.  Operationalization refers to defining otherwise abstract concepts or terms in a measurable way.  For example, “economically productive” can be operationalized as “dollars earned per day,” “hours worked in a week,” or “number of objects successfully produced at work.”  As we can see, a researcher must be careful to operationalize the measures in such a way that they reflect exactly what the researcher is trying to measure.  Depending on how terms are operationalized, the results of a study can vary widely, so it is critical that a researcher carefully consider how each of the measures are to be operationalized beforeforming a hypothesis and beginning a study.

A hypothesis takes the operationalized definition of the factors to produce a clear prediction of the causal relationship between the independent variable and the dependent variable in the statement.  The independent variable is a factor that the researcher can control or manipulate (whether or not a person receives basic eye care services), and a dependent variable is a factor that the researcher cannot manipulate, but instead varies in relation to the independent variable (the economic productivity of the individual).  For example, a hypothesis might be “We predict that if nearsighted participants are provided with corrective lenses that bring their vision to 20/20, they will earn more money per week on average over the course of three months than nearsighted participants who did not receive corrective lenses.”  This statement is a viable hypothesis because it clearly operationalizes what the researcher termed “basic eye care” and “economically productive” such that they can be measured and analyzed in an objective way.

When formulating a hypothesis, it is important not to try to “prove” that the hypothesis is true.  Instead, one should seek to find evidence that it is not true.  In other words, one can never accept a hypothesis; instead one fails to reject the null (posited) hypothesis.  This is especially important when using statistics such as t-tests and p-values to determine significance.


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