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Pepsi or Coke?

Pepsi or Coke?. Karim Ellithy ISC 3523C. Goals. Pepsi has the exclusive pouring rights contract for UF As researchers we are curious to find out whether or not the fact that UF only sells Pepsi has an effect on which cola drink students prefer

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Pepsi or Coke?

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  1. Pepsi or Coke? Karim Ellithy ISC 3523C

  2. Goals • Pepsi has the exclusive pouring rights contract for UF • As researchers we are curious to find out whether or not the fact that UF only sells Pepsi has an effect on which cola drink students prefer • We more importantly want to see whether UF students prefer Pepsi to Coke.

  3. Survey Subjects Testing a random sample of 50 UF students who passed through Marston Library between the hours of 2 and 4 pm on Thursday, February 27. Only “opinionated tasters” will continue with the questions about which soda they prefer and which they identify as Pepsi or Coke.

  4. Null Hypothesis Our null hypothesis supports the idea that most of our subjects will be able to taste a difference. The subjects are like a fair coin; they are just as likely to pick Pepsi as they are likely to pick Coke. p=0.5

  5. Alternate Hypothesis UF students will prefer Pepsi over Coke. p>0.5

  6. The Actual Test • We gave each subject a sample of Pepsi and a sample of Coke without them knowing which one is which. • We asked if they tasted a difference. • If they detected a difference, we asked which did they prefer. • Then we asked them to identify which they thought was Pepsi.

  7. Data Question 1: Did you detect a difference? (This field requires a Yes or No answer) Question 2: If so, which soda did you prefer? (Possible answers: Right, Left, No preference) Question 3: Which do you think is Pepsi?

  8. Results • Proportion of participants able to taste the difference between Coca-cola and Pepsi-cola: 40/50 = 0.80 (11.31% margin of error) • Tasters who prefer Pepsi: 23/40 = 0.575 with15.49% MOE • Tasters who prefer Coke: 13/40 = 0.325 with14.81% MOE • Tasters without a preference: 3/40 = 0.075 with 8.33% MOE • Tasters who correctly guessed which soda is Pepsi: 30/40 = 0.75 with 13.69% MOE • Tasters who incorrectly guessed which soda is Pepsi: 9/40 = 0.225 with 13.21% MOE • Tasters who did not know which is Coke: 1/40 = 0.025 with 4.94% MOE

  9. The Percentage Breakdown Pepsi=60% Coke=32.5% No preference=7.5% So do we reject/accept the null hypothesis or do we reject/accept the alternate hypothesis? BE CAREFUL!!

  10. Actual Z-score z-score = Pactual – Pnull √Pnull(1- Pnull) N 0.6– 0.5 √(0.5)2 = 1.265 40 • With a confidence level of 95%, our z-score would have had to have been 1.65 to be able to reject the null hypothesis

  11. Critical Region • P ≥ pnull + [z0 √pnull (1- pnull)] /N • P ≥ .6202 • Our critical region at the 5% level is P ≥ 0.6202 • Unfortunately, our P = 0.6 so we must assume that more students chose Pepsi over Coke due to chance.

  12. Decision: Null or Alternate? • In the end, we found that we had to reject our alternate hypothesis. • A Type I error ocurred

  13. Our Analysis • a Type I error occurred in which we had to reject our alternate hypothesis and we were forced to accept our null hypothesis • Because of our results, we cannot accurately assume that UF students prefer Pepsi, despite Pepsi’s abundance on campus

  14. Confounding Factors • Inadequate pallet cleansers, ie. Lays Potato Chips, the salt hindered our subjects from tasting objectively. • It was not completely randomly selected. Even though we asked many strangers to participate in our test, there were quite a few of our subjects who are friends.

  15. Acknowledgments Jacob Hughes: The pourer made sure that the odd numbered cups contained Pepsi on the left and Coke on the right while the even numbered were filled with Coke on the left and Pepsi on the right. Navaneet Patel: The distributor made sure that the left and rights corresponded correctly for both the pourers and the test administrators. Karim Ellithy: The test administrators asked the subjects the survey questions

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