Introduction to Biological Sciences lab, first semester

**Criteria** for choosing the correct test:

*t*** test of means: **

–values are continuous

–there is no reason why a particular value in one group would be related to a particular value in the other group

–comparing two group means

**paired t test:**

–values are continuous

–there is a connection between particular values in one group and corresponding values in the other group

–comparing differences between pairs of values in the two groups

**linear regression:**

–values are continuous

–values representing the experimental factor vary continuously rather than fall into discrete categories

–determining whether the line of best fit has a slope greater than zero

Appropriate **null hypotheses** for the statistical tests discussed: **(NOTE, these are generalized forms and should be adjusted for the specific factor(s)/group(s) being tested)**

*t*** test of means: **

–The means of the two groups are the **same** (i.e. differences in sample means are due only to chance).

**paired t test:**

–The difference between pairs of blocked data is **zero** (i.e. pairs of blocked data deviate randomly)

**linear regression:**

–The slope of the best fit line through the data is **zero** (i.e. deviations from a best-fit line having slope of zero are random).