# Exercise 3. Data Curation & ANOVA

###### tags: `exercise`

## Instructions

- Below are Problems which should all be achievable using the information from class. The Challenge will require you to find resources or answers on your own.
- **Please complete this assignment in groups of two** or three.
- Create a HackMD note to share your answers to these prompts. Include your names. Copy the prompts, add your code and explanatory text and images. Use markdown formatting to distinguish the prompts from the code and explanatory text of your answers.
- Submit your answers by sharing the note with Dr. Angelini before Friday at dawn.

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### General considerations

Data sets are not always perfect. They can contain missing data and data that are incorrect. Carefully examine the data you use in the problems below. Consider excluding data you deem unreliable. What, if anything, have you excluded? Justify your decision.

### Problem 1

Traits often scale with overall body size. Larger penguins will have larger bills and flippers, in general. So, when comparing these traits among species and sex, biologists will often "normalize" trait value by dividing them by the individuals body weight.

Create histograms showing the distribution of normalized bill lengths for each species and sex in the `palmerpenguins::penguins` dataset. Include a few short sentences offering a biological interpretation of these data.

### Problem 2

Is there a species-specific effect of sex on normalized bill length?

Think about how to test this question statistically. Conduct the test in R and share your code. Interpret the results of the test in text, the way you would in a journal article. Briefly discuss any violations of test assumptions you may have made and why.

### Challenge

Test the hypothesis from Problem 2 using the same data in a test that avoids parametric assumptions.

This is a difficult challenge! I am including it because I'd like you to think about how you could approach this problem. Include your thoughts or ideas even if you aren't able to fully implement a solution.

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