Statistics Ch 14

• The confidence level C determines the value of z* (in Table C).
• The margin of error also depends on z*.

• 
• Higher confidence C implies a larger margin of error m (thus less precision in our estimates).

A lower confidence level C produces a smaller margin of error m (thus better precision in our estimates).

• The spread in the sampling distribution of the mean is a function of the number of individuals
• per sample.

The larger the sample size, the smaller the standard deviation (spread) of the sample mean distribution.

But the spread only decreases at a rate equal to √n.

• the probability that the test will reject Ho at a significance
• level α when Ha is true.

Ho is rejected when it is actually true

Failure to reject Ho when in fact Ha is true