# T-Test

### Hypothesis Testing and the Statistics T-Test

The t-test is probably the most commonly used
Statistical Data Analysis procedure for
hypothesis testing.
Actually, there are several kinds of t-tests, but the most common is the "two-sample
t-test" also known as the "Student's t-test" or the "independent samples
t-test".

### T-Test Example

The two sample t-test simply tests whether or not two independent populations
have different mean values on some measure.

For example, we might have a research hypothesis that rich people have a different quality of life than poor people. We give a questionnaire that measures quality of life to a random sample of rich people and a random sample of poor people. The null hypothesis, which is assumed to be true until proven wrong, is that there is really no difference between these two
populations.

We gather some sample data and observe that the two groups have different
average scores. But does this represent a real difference between the two
populations, or just a difference in our particular sample, which might not be representative of the true population (e.g. unlucky random sample, or convenience sampling etc.).

### T-Test Statistic

The statistics t-test allows us to answer this question by using the t-test
statistic to determine a p-value that indicates how likely we could have gotten
these results by chance, if in fact the null hypothesis were true (i.e. no difference in the population). By convention, if there is less than 5% chance of
getting the observed differences by chance, we reject the null hypothesis and
say we found a statistically significant difference between the two groups. See
Statistical Data Analysis for more
information about hypothesis testing.

### Get the Statistics Help you need

When you hire me to do the data analysis for your
dissertation results chapter,
I carefully determine which statistical methods
are appropriate for your research. The t-test using SPSS
is simply one of the many statistical tests I can perform for your data. As with
any test I use for your dissertation, I include readily available
statistics help to ensure that you
understand how to interpret and report the results of your statistical analysis.

Simply contact me by phone or email to get started.

Steve Creech

630-936-4771 | Steve@StatisticallySignificantConsulting.com

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