# Sample Std Deviation and Sample Covariance using TI BAII Plus pro

Can someone please tell me how to calculate sample standard deviation and sample covariance using the TI BAII Plus Pro. Also, when the question tells us to find the Covariance (like in the CFAI Mock) do we find sample covariance or normal covariance? I believe that I got incorrect answer because I did not use sample covariance.

enter the data, then when you go into the stat mode, sx will be the sample stdev (sigma x being the normal stdev). To get covariance, scroll down to r, this gives correlation to divide by the stdev’s that you need (normal ones or sample). I know exactly which question you’re talking about I did the same thing. If it gives you a table of probabilities then its normal covraiance that you want. You want sample cov when you’re estimating from data.

thanks man

Am I the only one who does these by hand?

I do it by hand too. I am not sure if I want to learn the calc key strokes now and make a mistake in the exam in stat mode.

kurupt1 Wrote: ------------------------------------------------------- > enter the data, then when you go into the stat > mode, sx will be the sample stdev (sigma x being > the normal stdev). To get covariance, scroll down > to r, this gives correlation to divide by the > stdev’s that you need (normal ones or sample). > > I know exactly which question you’re talking about > I did the same thing. If it gives you a table of > probabilities then its normal covraiance that you > want. You want sample cov when you’re estimating > from data. If you use this formula, you would have population covariance…not sample covariance…right? Any way to get sample covariance out of the calculator?