Excel 2007:

CLICK GO:

- Go to the DATA ribbon
- Select the DATA ANALYSIS MENU (below)

- Select the data ranges and set the alpha (critical P) level:

The results of the dependent t-test can be seen in the resultant table. The value of t (t Stat) is -4.53744, which we can round off to -4.54.

The probability of this result being due to chance can be read from the table as 0.000291 (two-tail) which means that this result is significant at the .0003 level.

We will set our alpha level as .05, so we will say that p < .05 rather than that p = .0003.

We could also look up the t critical value or cut-off value for t from the table by looking at t Critical one-tail which is 2.110 without using the spreadsheet.We now have all the information we need to complete the six step statistical inference process:

State the null hypothesis and the alternative hypothesis based on your research question.

Null hypothesis: There is no significant difference between the height of the two samples of snail shells.

Alternative hypothesis: There is a significant difference between the height of the two samples of snail shell.

Set the critical P level (also called the alpha level )

P=0.05

Calculate the value of the appropriate statistic. Also indicate the degrees of freedom for the statistical test if necessary.

t = -4.53

df = 17 (unpaired , unequal sample variance)Write the decision rule for rejecting the null hypothesis.

Reject null hypothesis since t is <= -2.110Write a summary statement based on the decision.

Reject null hypothesis , p < .05, two-tailedWrite a statement of results in standard English.

There is a significant difference between the height of snail shells in the two samples.