Analyzing proportions

A proportion takes a value between zero and one. We often use this type of statistic to describe a population, e.g. the proportion of trees in a forest affected by mountain pine beetle. This page has information for estimating a population proportion and testing hypotheses regarding population proportions.

 
 
An introduction to what statistics is and why we need statistics to answer some biological questions.
 

Analyzing Proportions

The binomial distribution and the binomial test provide us with tools to be able to calculate P-values and test hypotheses when we are interested in the proportion of a sample that belongs to a certain category.

Additional Resources

Whitlock & Schluter - The Analysis of Biological Data

Chapter 7: pages 179-192 [Sapling]

 

Testing for the population proportion

Intro: Example of a hypothesis test for a proportion.

 

Estimating a proportion

Intro: Example problem requiring us to estimate a population proportion with confidence intervals.

 

Review Questions

 

  1. What probability distribution describes the number of “successes” in a fixed number of independent trials?

  2. What statistical test can be used to test whether the proportion of “successes” matches a null expectation?

  3. How do we estimate the standard error of a proportion?

  4. How would you determine a confidence interval for a proportion?

The Next Steps

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