Topics
Definition
Formula
Examples
Transaction Details
Definition
Formula
Formula (Continued)
 where Σ = Sum of
X = Individual score
M = Mean of all scores
N = Sample size (Number of scores)
 s = square root of[(sum of Xsquared -((sum of
X)*(sum of X)/N))/(N-1)]
Example
 To find the Standard deviation of 1,2,3,4,5.
Step 1: First, square each of the scores.
X
1
2
3
4
5
X2
1
4
9
16
25
Example (Continued)
 Step2: Use the formula
s = square root of[(sum of Xsquared -((sum of
X)*(sum of X)/N))/(N-1)]
= square root of[(55-((15)*(15)/5))/(5-1)]
= square root of[(55-(225/5))/4]
= square root of[(55-45)/4]
= square root of[10/4]
= square root of[2.5]
s = 1.58113
Transaction Details
 Following data elements are capture:
 Min
 Max
 Average
 Standard Deviation
 Initiated Count
 Completed Count
 Failure Percentage
 Transaction Rate/Sec (TPS)
Standard Deviation gives the true picture of variation in
response time.
Transaction Details – Example1
Transaction
eg. Login Page
Duration
1
0.929
2
3.779
3
0.524
4
3.987
5
1.412
6
0.222
7
2.603
8
1.139
9
10
2.187
0.499
Average µ
1.728
Stand-Dev. σ
1.3580
Transaction Details – Example2
Transaction
eg. Login
Page
Duration
1
0.979
2
1.001
3
1.021
4
0.987
5
1.012
6
0.922
7
1.203
8
1.139
9
10
1.187
0.999
Average µ
1.045
Stand-Dev. σ
0.095