formula for converting percentile to T-score or z-score

[jmmain24]

Hi all,

Does anybody know of an excel formula to convert percentiles to T-scores/z-scores?

Any guidance or tips would be greatly appreciated... thanks!

 

[Stephen_IV]

http://neuropsychnow.com/2014/05/excelCalculator

 

[jmmain24]

Thanks Stephen. The video referenced on the page appears to be broken though.

 

[Stephen_IV]

Found another link that may help out! You are right the video does not work! Sorry!

http://neuropsychnow.com/2013/07/ExcelNormSdist

 

[jmmain24]

I really appreciate your attempts Stephen

I actually already have all the referenced formulas from that page that tell me how to convert z's, t's, scaled scores, and standard scores to percentiles (I use all of them currently), but I do not have a formula that addresses how to calculate known percentiles into z's, T's, scaled scores and standard scores... if that makes sense. Essentially, I have some scores that are provided into %ile formats, but do not have the associated z or T score and I don't want to have to use a calculator to manually figure it out, if excel can just calculate that for me.

It seems your first reply hinted at how to do that but (as we both discovered) the video tutorial isn't operable to display the how-to.

 

[Stephen_IV]

OK I think this is what you are looking for if you have 0.98 in A1 you need =NORMSINV(A1) to get a zscore. if you have 98% in A1 then =NORMSINV(A1/1)

 

[Stephen_IV]

http://cedu.niu.edu/~walker/statistics/Percentile to Z2.pdf