# Statistics and Population Mean

**Topics:**Statistics, Null hypothesis, Standard deviation

**Pages:**2 (398 words)

**Published:**January 16, 2011

b) Increasing the population standard deviation.

The standard deviation is the factor that is used to divide by in the equation. the bigger the SD, then the smaller the z score.

c) Increasing the number of scores in the sample.

Should bring the samples mean closer to the population mean so z score will get smaller.

4a) The boundaries for critical region, when alpha level is is changed from α = .05 to .01, the size of the critical region will increase in size and the boundaries will be closer to the center of the distribution. This will allow me to see if there is error or not and also accept or reject the null hypothesis. If the alpha level is changed from .05 to .01 a) what happens to the boundaries for the critical region?

It reduces the power of the test to prove the hypothesis.

You increase the chance of rejecting a true H

b) what happens to the probability of a type 1 error?

Type 1 error is falsely reporting a hypothesis,

Where you increase the chance that you will reject a true null hypothesis.

4b) The probability of a Type I error is determined by the alpha level. Since the alpha level has decreased, we can expect increase in error. 6a) The independent variable is the application of study –skills training program and the dependent variable is the standardized achievement test. 6b) 6) A researcher is investigating the effectiveness of a new study skills training program for elementary school childreen. A sample of n=25 third grade children is selected to participate in the program and each child is given a standardizrd achievement test at the end of year. For the regular population of third grade children, scores on the test form a normal distribution with a mean u = 150, and a standard deviation q = 25....

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