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 )
- 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 <= -2.110
- Write a summary statement based on the decision.
Reject null hypothesis , p < .05, two-tailed
- Write a statement of results in standard English.
There is a significant difference between the height of snail shells in the two samples.