# two-population pooled t-test vs unpooled t-test

In a study of the lizard Sceloporis occidentalis, researchers examined field-caught lizards for infection by the malarial parasite Plasmodium. To help assess the ecological impact of malarial infection, researchers tested 15 infected and 15 noninfected lizards for stamina, as indicated by the distance each lizard could run in 2 minutes.

The distances (in meters) are shown in the table below.

Infected: 16.4 29.4 37.1 23.0 24.1 24.5 16.4 29.1 36.7 28.7 30.2 21.8 37.1 20.3 28.3

Noninfected: 22.2 34.8 42.1 32.9 26.4 30.6 32.9 37.5 18.4 27.5 45.5 34.0 45.5 24.5 28.7

Do the data provide evidence that this malarial infection is associated with decreased stamina? Do a complete write up. Be sure to justify the use of whatever test you decide on.

Step-by-step explanations are given.

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#### Solution Summary

First determine whether a t-test is appropriate.

Describe histograms and boxplots (analyze data).

Next, we need to figure out which t-test to perform, the pooled or unpooled, and then perform calculations to draw conclusion.