What is the goal if this chapter? How can these methods be used?
On an unrelated note, visit http://www.infoplease.com/p/brainpop/basicprobability.html for a quick review of basic probability.
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3 comments:
Write out the null and alternative hypotheses. Words and symbols would be nice. Be sure to follow the rules we talked about in class today re: the "equals" expression and parameters.
How exciting that you want to do SCAD!! SCAD applies whenever you are expected to use inference. That means whenever you generate a confidence interval or perform a hypothesis test. In tonight's homework you are only beginning to do the S part--setup. We're taking the first step by stating our hypotheses clearly, carefully, and correctly. :)
This is not a sample proportion problem. You don't use p-hat unless your parameter and statistic of interest are proportions of successes.
How do you know that this is not a proportion when the values look like percentages? The first thing to look for is whether you can define what a success is in binomial-type terms. This would be a case like the number of heads in 10,000 flips of a coin. A success is a head. In problem 10.28 there is no "success." Instead, the percentage measures a relative amount of money spent.
Frequently (although not in this particular case), one quick way to figure it out is to see if the percentages could be negative or more than 100%. If this is true, then it CAN'T be a proportion problem.
In this case you are using mu, x-bar, and the standard deviation of x-bar.
Good luck.
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