Understanding the P value

The smaller the p-value...

stronger the evidence against the null hypothesis

Steps to calculate P-value

1. Assume Ho is true 2. Draw sampling distribution 3.Identify statistic 4. Shade away from center 5. Calculate probability

large p-value

A large p-value (> 0.05) indicates weak evidence against the null hypothesis, so you fail to reject the null hypothesis.

What does the p value mean

In statistics, the p-value is the probability of obtaining results at least as extreme as the observed results of a statistical hypothesis test, assuming that the null hypothesis is correct. .

General Multiplication Rule

P(A and B) = P(A) * P(B|A)

p-value

The probability level which forms basis for deciding if results are statistically significant (not due to chance).

Central Limit Theorem

The theory that, as sample size increases, the distribution of sample means of size n, randomly selected, approaches a normal distribution.

Formula p value

To find the P value find the test statistic t = (x-μ) / (s/√n) where x is the sample mean, μ is the hypothesized mean (in our example it would be 15), s is the sample standard deviation, and n is the sample size.

68-95-99.7 rule

in a normal model, about 68% of values fall within 1 standard deviation of the mean, about 95% fall within 2 standard deviations of the mean, and about 99.7% fall within 3 standard deviations of the mean