Comparison of two groups using z and t-tests
| Paired test | Unpaired test |
|---|---|
| Deals with the difference between the paired values | Deals with the difference between the means of both groups |
| Relies on the population of this difference being normally distributed | Relies on the population of this difference being normally distributed |
| It is not affected by the distribution of the before and after samples | Is affected by the inter and intra group distribution |