# I'm confused about the P-value

What's the formula to calculate the p-value in this video?

Hello,

Given that the T value is equal to 0.53, we can obtain the p-value from the t-distribution table considering n-1 degrees of freedom.

Best,

Ned

In the lesson the teacher say that formula 1- the number from the table, it uses with z-distribution table . is it use also with t-distribution table?

We use the n-1 degrees of freedom for T tests. A Z test does not use degrees of freedom. At which moment of the video is it said that a Z test used n-1 degrees of freedom, please?

I edit my last comment so can you look again?

T value is 0.53 and n-1 degrees is 9. But How the p-value 0.304 is obtained ? I do not see how to get that value from the t table? it is 1 - something? Or just need to be calculated with the online tool

Manuel Carreno Yes , it was calculated through online calculator

There is still no information about how the p-score is calculated from the t-table.

As far as I know, there are 2 ways of getting the p-value.

1. Using a p-value calculator. Go to https://www.socscistatistics.com/pvalues/ and choose, in this case, p-value from t score. You will need to input the T score (which is obtained from substracting the hypothesized mean to the sample mean, and then dividing by the standard error; 0.53), the degrees of freedom (sample size minus 1; 9), the significance level (0.05), and whether it is a one-sided or a two-sided test (one-sided in this case).

The result is p-value = 0.304. If the p-value is higher than the significance level (α), which in this case it is (0.304 > 0.05), the result is not significant, meaning we must accept the null hypothesis.

2. Using one of these Excel formulas: **T.DIST** ("returns the left-tailed Student's t-distribution"; I believe this means that H0 is less than or equal to some value), **T.DIST.2T** ("returns the two-tailed Student's t-distribution"; this would apply to the exercise of this lesson, where we are looking for a hypothesized mean of exactly 40%), or **T.DIST.RT** ("returns the right-tailed Student's T distribution"; this must apply when H0 is greater than or equal to some value).

The arguments for T.DIST are (x=[T-score value (use positive values preferrably, as the T.DIST.2T formula won't accept negative ones)], deg_freedom, cumulative = TRUE (don't understand the mechanics of this argument, but choosing FALSE will give us a value that differs from the calculator's, so better to stick to TRUE)).

Hope this helps.