# One sample t-test

## Description

Use the one sample t-test to test whether the average of observations differs significantly from a test value.

## Required input

- Select the variable of interest.
If the variable needs Logarithmic transformation, select the corresponding option.

- Optionally select a filter to include a subset of cases.
- Test value: the value to which you want to compare the sample mean.

## Results

The results include the summary statistics of the observations.

The One sample t-test panel shows:

- The test value
- The difference Sample mean - Test value
- The 95% Confidence Interval (CI) for this difference
- The Degrees of Freedom (DF), t-statistic, and corresponding (two-sided) P-value.

If the calculated P-value is less than 0.05, the conclusion is that, statistically, the sample mean is significantly different from the test value.

### Logarithmic transformation

If you selected the Logarithmic transformation option, the program performs the calculations on the logarithms of the observations, but reports the back-transformed summary statistics.

For the One sample t-test, the difference between sample mean and test value, with 95% confidence interval, are given on the log-transformed scale.

Next, the results are transformed back and the interpretation is as follows: the back-transformed difference of the logs is ratio of the sample mean / test value on the original scale.

## See also

## Link

Go to One sample t-test.