Presentation is loading. Please wait.

Presentation is loading. Please wait.

Cross Tabs A frequency distribution for two variables.

Similar presentations


Presentation on theme: "Cross Tabs A frequency distribution for two variables."— Presentation transcript:

1 Cross Tabs A frequency distribution for two variables

2 M&Ms Color Distribution % according to their website BrownYellowRedBlueOrangeGreen Plain Peanut

3 We take a sample of M&M’s and find a sample distribution to compare to the website distribution

4 My M&Ms data in counts BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total

5 14 of the 76 M&M’s were plain brown M&M’s BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total

6 54 of the 76 M&M’s were Plain BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total

7 8 of the 76 M&M’s were blue BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total

8 Probability To find the probability: N(event)/N(total) P(peanut green M&M) = –N(Peanut Green)/N(Total M&M’s)

9 To find Joint Distribution, we find the probabilities of each cell by dividing by the total (76) BrownYellowRedBlueOrangeGreenTotal Plain 14/7610/76 8/764/768/7654/76 Peanut 2/763/765/760/768/764/7622/76 Total 16/7613/7615/768/7612/76 76

10 My M&Ms data: With Marginal Distributions BrownYellowRedBlueOrangeGreenMarg. for flavor Plain Peanut Marg. for color

11 Knowing that the M&M is green, what is the probability it was Peanut? BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total We can focus on just the green column so the probability of Peanut is: N(Green Peanut)/N(Green) = 4/12

12 Conditional distribution of flavor for color We know the color of our M&M already, but now how is flavor distributed for this color?

13 Knowing that the M&M is Plain, what is the probability it is Yellow? BrownYellowRedBlueOrangeGreenTotal Plain Peanut Total We can focus on just the Plain row so the probability of Yellow is: N(Yellow Plain)/N(Plain) = 10/54

14 Conditional distribution of color for flavor We know the flavor of our M&M already, but now how is color distributed for this color?

15 Conditional distributions in general Conditional distribution of X for Y (we know Y for sure already, but we want to know the probability or % of having X be true as well):

16 Bar graphs for conditional distribution of color for both flavors

17 Joint Distribution (In white boxes) Marginal (In gray boxed) Conditional (Given color or flavor) BrownYellowRedBlueOrangeGreenMarg. for flavor Plain Peanut Marg. for color


Download ppt "Cross Tabs A frequency distribution for two variables."

Similar presentations


Ads by Google