Wednesday, September 5, 2012

Testing the Difference between Two Means (Large Samples)



Teachings of Ma’am Macatigos made us learn of how to use Microsoft Excel in performing Hypothesis Testing, just like in the topic: Testing the Difference Between Two Means (Large Sample). According to the handouts that ma’am gave us this are the steps:

1.       Enter the first sample data set in column A.
2.       Enter the second sample data set in column B.
3.       If the population variance are not known, but n≥30 for both samples, use the formulas =VAR(A1:An) and  =VAR(B1:Bn) where An and Bn are the last cells with data inn each column, find the variances of the sample data set.
4.       Select TOOLS, DATA ANALYSIS, and choose Z-TEST: TWO SAMPLE FOR MEANS.
5.       Enter the ranges for the data in column A and B and enter 0 for the hypothesized Mean Difference.
6.       If the population variances are known, enter them for variable 1 and variable 2. Otherwise, use the sample variances obtained in step 3.
7.       Specify the confidence level, ALPHA.
8.       Specify a location for output, and click.
A researcher wishes to see if the average length of the major rivers in the United States is the same length of the major rivers in Europe. The data in miles of a sample
of rivers are shown. At α=0.01, is there evidence to reject the claim?





Identify the Null and Alternative Hypothesis and the claim.
µ1 =Major rivers in the United States                                µ2 = Major rivers in Europe
H0:  µ1 =  µ2  (claim)
H1:  µ1   µ2

Make your decision whether to reject or not to reject the Null Hypothesis:
Do not reject the Null Hypothesis, since the test value falls outside the critical region.
Summarize the results:
There is not enough evidence to reject the claim.

If the steps are followed correctly, you will obtain the answer easily and accurately. This lesson showed  me of some other uses of Excel. Amazing is it that Microsoft Excel can be a very good tool for us, statisticians.

Posted by: Kent Spencer Manalo Mendez
                                 III-Gold

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