```Date: Fri, 19 Mar 1999 09:50:35 -0300 Reply-To: GLAUBERF@VAREJO.COM.BR Sender: "SPSSX(r) Discussion" From: Glauber Fonseca Subject: Test if Samples are Dependent or Independent Content-type: text/plain; charset=us-ascii Hi, everbody. I am facing some problems interpreting SPSS 8.0 for Win results. This is what I want: I know the consumption of a certain material for the last 36 months. Based on this history, I need to foretell the consumption for the next 12 months.Through the Monte Carlo technique I got to the consumption for the next 12 months, based on the history consumption. So now I have two samples (1- 36 numbers, 2 - 12 numbers. I have to test if sample 2 (12 elementes) belong to the same distribution of sample 1 (36 elements). I have done the T-Test for 2 independent Samples and got the results shown below: - Group Statistics: Grupo 1 (hystorical data): N: 36 Mean: 4021,305 Std. Deviation: 2913,4024 Std. Error Mean: 485,5671 Grupo 2 (forecast): N: 12 Mean: 3083,3333 Std. Deviation: 2193,3094 Std. Error Mean: 633,1539 - Independent Samples Test: Levene's Test for Equality of Variances: F = 3,222 Sig. = 0,079 - Equal variances assumed: t-test for Equality of Means: t = 1,020 df = 46 Sig. (2-tailed): 0,313 Mean Difference = 937,9722 Std. Error Difference = 919,4538 95% Confidence Interval of the Difference: Lower = -912,7923 95% Confidence Interval of the Difference: Upper = 2788,7367 - Equal variances not assumed: t-test for Equality of Means: t = 1,176 df = 25,024 Sig. (2-tailed): 0,251 Mean Difference = 937,9722 Std. Error Difference = 797,9093 95% Confidence Interval of the Difference: Lower = -705,2740 95% Confidence Interval of the Difference: Upper = 2581,2185 How can I say sample 2 belongs or does not belong to the same distribution of sample 1 with a 95% confidence level? Which results should I compare ? Please describe it in details. Can you help me ? Is this the best test I can do ? Or should I do another ? TIA, Glauber Fonseca ```

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