1 / 8

Chi squared

Chi squared . A biologist randomly selects 20 fruit flies. All of them are placed in a tube with vinegar on one side and mustard on the other side. Do these fruit flies have a preference for either mustard or vinegar? The results are listed below. mustard : 5 vinegar: 15 .

zudora
Download Presentation

Chi squared

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chi squared

  2. A biologist randomly selects 20 fruit flies. All of them are placed in a tube with vinegar on one side and mustard on the other side. Do these fruit flies have a preference for either mustard or vinegar? The results are listed below. mustard : 5 vinegar: 15 First name the test. χ2 Goodness of Fit Test.

  3. A biologist randomly selects 20 fruit flies. All of them are placed in a tube with vinegar on one side and mustard on the other side. Do these fruit flies have a preference for either mustard or vinegar? The results are listed below. mustard : 5 vinegar: 15 χ2 Goodness of Fit Test. Write the hypotheses Ho : Fruit flies are equally drawn to mustard and vinegar. Ha : Fruit flies are not equally drawn to mustard and vinegar.

  4. A biologist randomly selects 20 fruit flies. All of them are placed in a tube with vinegar on one side and mustard on the other side. Do these fruit flies have a preference for either mustard or vinegar? The results are listed below. mustard : 5 vinegar: 15 χ2 Goodness of Fit Test. Ho : The fruit flies are equally drawn to mustard and vinegar. Ha : The fruit flies are not equally drawn to mustard and vinegar. Conditions The fruit flies are randomly selected is given. Data are categorical (or counts). All expected values are ≥ 5. Expected counts for each group = 10

  5. Calculate χ2 Degrees of freedom = 2 – 1 = 1

  6. χ2 = 5 df= 1 .025 < p-value < .05

  7. Biology table for chi-squared critical value approach So how much proof do you need?

  8. χ2 Goodness of Fit Test. Ho : The fruit flies are equally drawn to mustard and vinegar. Ha : The fruit flies are not equally drawn to mustard and vinegar. Conditions The fruit flies are randomly selected is given. Data are categorical (or counts). All expected values are ≥ 5. Expected counts for each group = 10 χ2 = 5 > 3.84 df = 1 .025 < p-value < .05 Conclusion Reject Ho since the p-value < α = .05 (or since χ2 > critical value 3.84) We have evidence that fruit flies do have a preference. They appear to prefer vinegar over mustard. Ta Da!

More Related