Test: Mean: SD: HCT # X Difference from X Squared Difference from X Range +/- 1SD Range +/- 2SD 34 . 8 Range +/- 3SD 2 34 . 9 3 35.0 4 35. 2 Procedure for calculating mean and 5 35- 4 standard deviation: 6 35. 6 1. Record control data into the first column 2. Find the sum of column one by adding 7 35. 8 all values together 8 35. 8 3. Calculate the average, X 4. Calculate and record in column two 9 36.0 individual differences from the average 36.0 5. Square each individual difference in 10 column two, and record in column three 11 36.0 6. All column three to get the total 7. Calculate the Standard Deviation using 12 36.2 the equation below 13 36. 4 X = each individual measurement 14 36.4 N = total number of measurements 15 36 . 4 X = mean 16 36. 6 Mean = Sum of X 17 36.8 N 18 37.0 Standard Deviation = 19 37.0 Sum of Squared Difference from X 20 37. 2 N-1 Sum 37