p value

[Questions]

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How do you find p-value? I've looked online, and i get conflicting and unclear answers. i've read wikipedia..and still kind of confused. actually, do i even have to understand it for QR?

 

[Moabmad]

My limited understanding is that P-values can be calculated in different ways... chi square, T test...... but basically its the value that determines whether your values are statistically significant or within reasonable data variance. Hence u can make the judgement as to rejecting/accepting the null hypothesis. Anyways, I did not have any questions on my DAT regarding p-values nor did any of my study materials have questions relating to it.

 

[NewBee12]

What i know and remember from statistics is in order to find the p-value you have to find the area to the left and to the right of the z-score. To find the z-score you use the following formula: z=(score-mean)/standard deviation. To find the area you need to use a table!!!! especially if the z-scores are not whole numbers. My suggestion is just remember the 68% 95% 99.7% rule and you should be fine
68% of the data lies within 1 standard deviation to the right and to the left
95% of the data lies within 2 standards deviations ......
99.7% of the data lies within 3 standard deviations ....

 

[Streetwolf]

What i know and remember from statistics is in order to find the p-value you have to find the area to the left and to the right of the z-score. To find the z-score you use the following formula: z=(score-mean)/standard deviation. To find the area you need to use a table!!!! especially if the z-scores are not whole numbers. My suggestion is just remember the 68% 95% 99.7% rule and you should be fine
68% of the data lies within 1 standard deviation to the right and to the left
95% of the data lies within 2 standards deviations ......
99.7% of the data lies within 3 standard deviations ....

That's just one possible test. There are many other significance tests out there which will give you a p-value.

A p-value represents the probability that the results you got happened by chance.

A p-value of 0.05 means there's a 1 in 20 chance (5%) that your results came about randomly. That's good. You want your results to happen because there's some sort of correlation, not because they just happened to end up that way.