# Thread: Independent t-test p value 0.000? hmm

1. ## Independent t-test p value 0.000? hmm

What does a p value of 0.00 mean? I know below 0.05 shows significant difference at the 95% confidence level, but I think my teacher is testing us.

Now the means are different of the data being compared, however the independent samples equality mean test both have -.85963.

I think they have provided the data in such a way trick/test us . Can anyone help?

Independent Samples Test
Levene's Test for Equality of Variances t-test for Equality of Means
95% Confidence Interval of the Difference
F Sig. t df Sig. (2-tailed) Mean Difference Std. Error Difference Lower Upper
Organic_Matter_Content Equal variances assumed 5.872 .018 -9.617 82 .000 -.85963 .08939 -1.03745 -.68181
Equal variances not assumed -10.898 80.571 .000 -.85963 .07888 -1.01659 -.70266

2. Originally Posted by rtyrtyrtyus
What does a p value of 0.00 mean? I know below 0.05 shows significant difference at the 95% confidence level, but I think my teacher is testing us.

Now the means are different of the data being compared, however the independent samples equality mean test both have -.85963.

I think they have provided the data in such a way trick/test us . Can anyone help?

Independent Samples Test
Levene's Test for Equality of Variances t-test for Equality of Means
95% Confidence Interval of the Difference
F Sig. t df Sig. (2-tailed) Mean Difference Std. Error Difference Lower Upper
Organic_Matter_Content Equal variances assumed 5.872 .018 -9.617 82 .000 -.85963 .08939 -1.03745 -.68181
Equal variances not assumed -10.898 80.571 .000 -.85963 .07888 -1.01659 -.70266
What software are you guys using? SPSS? if so double click on the .000 pvalue to see the actual pvalue

3. comes with a pivot table and both still 0.000

4. Originally Posted by rtyrtyrtyus
comes with a pivot table and both still 0.000
You're using excel?

5. SPSS. I double clicked it in the output window

6. Originally Posted by rtyrtyrtyus
SPSS. I double clicked it in the output window
Oke, so it could be that SPSS just does not return values of p-values smaller that a certain threshold.

Calculating it myself: The p-value with a t score of -9.617 with 82 df is: 1.525775e-14.

The p-value is the probability of obtaining a result at least as extreme as the one the observed. So in this case SPSS says it is 0. It actually is 1.525775e-14 (which is for all practical purposes is 0).

Originally Posted by rtyrtyrtyus
Now the means are different of the data being compared, however the independent samples equality mean test both have -.85963.
That is the lower 95&#37; confidence interval, so both tests have a similar lower confidence interval. Your point here is?

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