[EMAIL PROTECTED] ([EMAIL PROTECTED]) wrote in message news:<[EMAIL PROTECTED]>... > I ran a z test on two sets of scores using the Excel data analysis > tool to seek to determine whether the difference in the means were > statistically significant. What I do not understand is how to read > the results of the z test Excel returns. It give me a "z", "P" one > tail and "P" two tail. Can anyone explain to me how to interpret > these results? Thanks.
I really do appreciate the time you folk took to respond, but I am still in the dark. So let me be a bit more explicit and see if what I need makes more sense. I am a sixth grade teacher. I have two sets of reading scores (standard scores with a range of 27 to 55). One set has 40 students and the other has 65. I enter each score in a column in Excel for each class. I get the mean, st. dev. and variance from Descriptive Statistics. On one test the difference in mean scores is less than 2 points. On another test the difference is 12 points. Common sense tells me there is a significant difference in the two sets of scores on the test with 12 points difference. My question is: is the difference of 2 points statistically significant or the result of chance? If my assumption is correct and one class did significantly better than the other on one test and on the other the difference in performance is (probably) not statistically significantly different then is that a correct assumption? So somewhere between 12 points and 2 points I can guess there is a significant difference but less than that it is not. I asked a math teacher how to determine that point on any given set of scores and was told to run a z test. I was told a t test is used to test whether a sample's mean is representative of the total population's mean. So I used a z test. In Excel what is returned is a "z" score, a P score for one tail and a P score for two tail for a hypothesized mean of .05. Can someone tell me how to interpret the numbers returned for z, P one tail and P two tail, assuming the z test is the correct procedure. If not, what do I use and how do I interpret the results Excel returns? . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
