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 χ 2 Goodness of Fit Test. First name the 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 χ 2 Goodness of Fit Test. Write the hypotheses H o : Fruit flies are equally drawn to mustard and vinegar. H a : 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 χ 2 Goodness of Fit Test. H o : The fruit flies are equally drawn to mustard and vinegar. H a : 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 χ 2 Degrees of freedom = 2 – 1 = 1

6. df = 1.025 < p-value <.05 χ 2 = 5

7. CHI-SQUARE TABLE Degrees of Freedom p12345678 0.053.845.997.829.4911.0712.5914.0715.51 0.016.649.3211.3413.2815.0916.8118.4820.09 Biology table for chi-squared critical value approach So how much proof do you need?

8. χ 2 Goodness of Fit Test. H o : The fruit flies are equally drawn to mustard and vinegar. H a : 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 df = 1.025 < p-value <.05 χ 2 = 5 > 3.84 Conclusion Reject H o since the p-value critical value 3.84) We have evidence that fruit flies do have a preference. They appear to prefer vinegar over mustard. Ta Da!