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intro.psych (Psyco 105) Discussion: Group 3 Discussion Group: Methods: Sites to Visit: Probability Demonstration
By Connie Varnhagen (Admin) on Tuesday, September 8, 1998 - 01:40 pm:
Try this coin flipping experiment.
The thing with flipping coins is that each flip has a .5 probability of being either heads or tails NOT the group of flips. (i.e. If the first flip is heads, the second flip still has a .5 probability) That's why the ratio might not be what it "should".
As you increase in sample size, randomness will prevail and you will see that the flipping of coins will get closer to 50% and the probability of winning a free coke will be 1/6
I must be lucky because with 10 coins I got 5 heads and five tails - exactly 50%. With 100 coins, on the other hand, I got 45 heads and 55 tails. In this case, increasing the sample size did not help the coins get closer to 50%.
With 10 coins I had 3 heads and 7 tails,but when I increased my sample size to 100 it moved to a 40 , 60 . SO as the sample size increases so does the accuracy of the prediction.
Sure MollyC go ahead and summarize. You can choose the part. I'll summarize next week!
Molly C if you want to summarize, go for it! Choose whatever topic you wish. I left a message about summarizing, choosing weekly topics under Lifestyle Questionnaire. Let me know what you think, maybe it is irrelevant...
This demostration of probability is quite effective. Using the computer to flip the coins makes it both efficient and accurate. Efficient because you can flip different numbers of coins quickly, thus showing you how sample size changes your results and not losing the participants interest. It is also accurate for these same reasons. The only problem I have with it is, the randomness of participants, but this is only relevant if trying to prove a hypothesis with the results.
Something to add to the summary, it was a unclear to .5 probability. The way it was explained the whole group probability was.5, but a group member pointed out that it was .5 for each coin and each toss.
Good job on the discussion. I was pleasantly surprised to see some generalizing of the topic to different experiences in your lives (e.g., the coke contest). That was very interesting and a good indication of your level of understanding on the topic. However, the summary did not cover some of the great points you guys made in the discussion. For the next time - try to incorporate ideas from all discussion members and address the site questions directly (e.g., you didn't explain how sample size affects the outcome). I hope to see more identification of some issues about the topic and a little more depth. Remember, you will be graded on 10 out of 11 summaries so you can forego one if you're not happy with the mark. Grade1+
We know that the probability of getting a head on any single flip is .5. Select a small number of flips (10) for the coin experiment. How closely do your results reflect the expected results for the experiment? If your results are not exactly whatthey "should" be, what does this show about the nature of probability? Select 100 flips. Do your results look more like expected results? What does this show about the importance of sample size?
Go There
By Montresor on Thursday, September 10, 1998 - 03:55 pm:
This can also be explained using the 600mL bottles of Coke when they have their contests. The usual probability of winning is 1/6. This doesn't mean that if you buy 5 bottles and none are winners that you can sue Coke if you don't win on the sixth, because each bottle has a 1/6 chance of winning not a group of bottles.
By Montresor on Thursday, September 10, 1998 - 03:58 pm:
By Jene on Sunday, September 13, 1998 - 11:38 am:
By Mollyc on Monday, September 14, 1998 - 02:26 pm:
This is also why people become addicted to gambling, they believe that if they keep spending they are going ot have to win. I don't know if anyone remembers that episode of Fresh prince where Carlton is trying to calculate probability for WIll. Will just Keeps winning, it didn't follow the rules of probability.
Which part do we want to summarize? I am willing to write it up.
By Montresor on Monday, September 14, 1998 - 05:01 pm:
By Jene on Monday, September 14, 1998 - 06:45 pm:
By Mollyc on Wednesday, September 16, 1998 - 01:03 pm:
By Mollyc on Wednesday, September 16, 1998 - 01:29 pm:
By Patricia on Wednesday, September 16, 1998 - 04:15 pm: