Warm Up Exercise: Preparing for the Chi-Squared Test
In this lab, you will be doing a statistical test called the chi-squared test to decide whether or not to reject your hypothesis based on the observations that you make. To begin, review the Statistics In Introductory Biology document, available from the assignment dropbox for this lab (this is the same document that you used for the Cells and Diffusion lab).
If you have not performed a chi-square test before, you may also wish to view the Understanding and Using the Chi-Squared Test video. (Note that this video was recorded for a similar lab in BIOL 1010, and may refer to other labs or activities that aren't relevant to this class; you can ignore these references.)
In your notes, answer the following question based on the reading and the video.
1. If your hypothesis gives a prediction of 3 curly-petal plants to 1 flat-petal plant, and you observe a total of 468 plants, how many curly-petal plants do you expect to see? Support your answer.
Check your answer to Question 1.
Consult the section of the Chi-Squared Critical Values table pictured below, and answer the questions that follow to make sure that you are comfortable interpreting this table. If you're not sure how to read the table, watch the Understanding and Using the Chi-Squared Test video for an example.
2. For a chi-squared value of 7.16, with one degree of freedom, what is the corresponding p-value?
Check your answer to Question 2.
3. Explain in words what "p = 0.25" means in the chi-squared test.
Check your answer to Question 3.