TI-83 Instructions
Computing a Sample Variance and Standard Deviation
Enter
the data into List L1.
Method
1 (Standard Formula)
- Compute the mean of L1. (See Computing a Mean.)
- Press L1.
- Press – (minus).
- Enter the mean.
- Press ENTER. The display shows a list of deviations.
- Press STO.
- Press 2nd L2.
- Press ENTER. The deviations are now stored in list L2.
- Enter the expression sum(L2^2).
- Press ENTER. The display now shows the sum of the
squared deviations, i.e., SS(x).
- Press ÷ (divide).
- Enter one less than
the sample size, i.e., n – 1.
- Press ENTER. This gives the variance.
- Press 2nd √ (square root). The symbols √(
appear.
- Press 2nd ANS. The expression Ans appears after the
square root. This refers to the
result of the previous calculation, which in this case is the variance.
- Press ).
- Press ENTER. The display now shows the standard
deviation.
Method
2 (Alternative Formula)
- Enter the expression sum(L1^2)
– sum(L1)^2.
- Press ÷ (divide).
- Enter the sample size.
- Press ENTER.
- The display now shows
the sum of the squared deviations, i.e., SS(x). From here on, follow steps 11 – 17
under Method 1.
Method 3
- Press STAT.
- Select the CALC menu title.
- Select the first item, 1-Var
Stats.
- Press ENTER. The phrase 1-Var
Stats
appears in the display.
- Press 2nd L1.
- Press ENTER. A list of statistics appears. The fourth one in the list, Sx, is the sample
standard deviation. (Be careful
not to use σx. It
represents the population standard deviation.)