Class Nine: Testing our Hypothesis
HW:
1a. 190 +/- 1.96*(35/sqrt(19)).
I am 95% confident that the average weight of a person on a plane with 19 passengers will be between 174.26 and 205.74 pounds.
1b. an average weigh of 4000/19 (210.53 pounds) gives a z value of 2.56.
That z gives a p-value of .9947. There is a 99.47% chance the average weight will be below this value.
2a. One person @ 590: 76.5% to score at least a 590. So a 590 or above...23.5%
2b. 16 people @ 590 or above: 99.8% score 590 or below, 0.2% to score this high to higher as a group.
2c. What does it mean to have evidence?
3. I expect the average weight in the elevator to be at or below 2520 97.72 percent of the time. This leaves 2.27% of the time where it would exceed that weight.
This comes out to being over the weight limit 100 times in a year.
4.
22% corresponds to a z score of ~ -0.77.
6% above (94% below) corresponds to a z-score of ~ 1.55.
set up two z score equations, leaving sd and mean blank. use appropriate methods (or the internet) to solve.
mean = 2.995 lbs
sd = 1.29 lbs.
Newt Salve, 2000
I have created this amazing newt salve, called NEWT SALVE 2000. It is supposed to help newts heal at a faster rate than they did before. Here are the healing times (remember, the sd of healing newts is 8 micrometers per hour):
23 27 31 39 27 23 42 30 30 44 18 28 32 28 28 29
the difference between hypothesis testing and the way that you think about the world
one tailed vs. two tailed ideas
How old are our pennies?
Pennies in circulation last about 25 years from what I can find online, in a fairly normal distribution of pennies.
Here's my question: Do the pennies I have in this tin differ in age from the average penny currently in circulation?
set up an experiment for us to consider to test this hypothesis
what is our goal? what are we trying to show/prove/believe?
what did we make with our sleep data?
problems with collection of data
finding the average time that people slept
what do our sweet graphs look like?
Extra:
A statistics professor at a large university believes that the students take an average of 15 credit hours per term. He samples 24 students in his class. We do not know the sd of the population, so use the sd of the class. Here are the results:
12 13 14 14 15 15 15 16 16 16 16 16 17 17 17 18 18 18 18 19 19 19 20 21
Analyze the data, and see whether or not the professors claim is reasonable. At the end of the question, include any possible biases or problems with the data collection.
HW:
Naked Statistics, Chapter 10: "Polling"
note: we are skipping chapter nine. I do not like this chapter and think it muddies up our waters. Regardless, you are welcome to read it if your heart desires.
Standard Deviations, Chapter 2: Garbage In, Gospel Out
This article: http://io9.gizmodo.com/i-fooled-millions-into-thinking-chocolate-helps-weight-1707251800