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3.2.2.1 Determining the Null Hypothesis and the Research Hypothesis
When Rating Scales are Used
Here is a typical example of a 7-point scale in science education for parents of 8th
grade pupils at the end of a school year (see Fig. 3.6 ):
Fig. 3.6
Example of a rating scale item for parents of 8th graders (practical example)
So, how do we decide what to use as the null hypothesis and the research
hypothesis whenever rating scales are used?
Objective: To decide on the null hypothesis and the research hypothesis
whenever rating scales are used.
In order to make this determination, we will use a simple rule:
Rule: Whenever rating scales are used, we will use the ‘‘middle’’ of the scale as the
null hypothesis and the research hypothesis.
In the above example, since 4 is the number in the middle of the scale (i.e.,
three numbers are below it, and three numbers are above it), our hypotheses
become:
Null hypothesis: l ¼ 4
Research hypothesis: l 4
In the above rating scale example, if the result of our statistical test for this one
attitude scale item indicates that our population mean is ‘‘close to 4,’’ we say that
we accept the null hypothesis that the parents of 8th grade pupils were neither
satisﬁed nor dissatisﬁed with the quality of the science program offered by their
son’s or daughter’s school.
In the above example, if the result of our statistical test indicates that the
population mean is signiﬁcantly different from 4, we reject the null hypothesis and
accept the research hypothesis by stating either that:
‘‘Parents of 8th grade pupils were signiﬁcantly satisﬁed with the quality of the
science program offered by their son’s or daughter’s school’’(this is true whenever
our sample mean is signiﬁcantly greater than our expected population mean of 4).
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