Statistics 200: Lab Activity for Section 4.2
Measuring Evidence with P-values - Learning objectives:
· Recognize that a randomization distribution shows what is likely to happen by random
chance if the null hypothesis
...
Statistics 200: Lab Activity for Section 4.2
Measuring Evidence with P-values - Learning objectives:
· Recognize that a randomization distribution shows what is likely to happen by random
chance if the null hypothesis is true
· Use technology to create a randomization distribution
· Interpret a p-value as the proportion of samples that would give a statistic as extreme as the
observed sample, if the null hypothesis is true
· Distinguish between one-tailed and two-tailed tests in finding p-values
· Find a p-value from a randomization distribution
Activity 1: Create a randomization distribution
This activity is meant to have you participate in the creation of a randomization distribution to
understand that it shows a distribution of sample statistics that were created assuming the null
hypothesis is true.
Every year in Punxsutawney, Pennsylvania a famous groundhog, Phil, makes a prediction about
the end of winter. If he comes out of his burrow and sees his shadow he predicts six more
weeks of winter. If he does not see his shadow, his prediction is an early spring. In the ten
years from 2007 to 2016 he has been correct seven times:
Year Prediction February Temperature Prediction accuracy
2016 End of winter Above Normal Correct
2015 More winter Below normal Correct
2014 More winter Below normal Correct
2013 End of winter Above normal Correct
2012 More winter Below normal Correct
2011 End of winter Below normal Incorrect
2010 More winter Below normal Correct
2009 More winter Above normal Incorrect
2008 More winter Above normal Incorrect
2007 End of winter Above normal Correct
Are his predictions better than a random 50-50 chance?
1. What are the correct null and alternative hypotheses? Hint – what is p if his predictions are
random?
H0: p =. 50-50 chance Ha:p > .5
2. What is p-hat when considering this example (round your answer to 4 decimal places,
0.xxxx)?
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.7
3. To create a randomization distribution, we must determine what the distribution of p-hat is if
his prediction is random. We will use virtual coins, which have a true 50% chance of being
heads. Go to justflipacoin.com.
How many times will you need to flip this penny to create one sample statistic for the
randomization distribution?
10
4. Now flip the penny that many times. Pretend that getting a heads with the coin is
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