Independent t-test p value 0.000? hmm

#1
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
 

TheEcologist

Global Moderator
#2
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
 

TheEcologist

Global Moderator
#6
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).


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% confidence interval, so both tests have a similar lower confidence interval. Your point here is?