What is 90th Percentile? Calculation of 90%?

90^th Percentile :

      

The 90% tells you the values for which 90% of the data points are smaller and 10% are bigger.

                                (OR)

The 90th percentile is the value for which 90% of the samples were less than that value

    

90the percentile means the highest response time among the best passed 90% of the attempts of the transaction.

 For an example, the transaction  passed for 20 times. So 90% of 20 values would be 18 i.e. LR will take 18^th value is the best response times for that transaction and will report highest among those. This in turn means (90 percentile means) 90% of the response times are less than or equal to this particular number

This 90th percentile value is considered as the benchmark

Statistical Steps to calculate the 90th percentile value:-

The 90th percentile is a measure of statistical distribution.The 90^th percentile tells you the value for which 90% of the samples were

less(Smaller) than that value and 10% are bigger.

Steps

1. Sort the transaction instances by ascending order.

2. Count the total number of transactions Say T.

3. Calculate 90/100 * T = Position (P)

4. This calculated position (P) contains the 90th percentile value (V).

Example 1:

There are certain instances of transaction "t" with the values 1,3,2,4,5,21,7,8,12,6,28,8,17,22,13,2,11,15,14,3 (in sec).

1.Sort by value -- 1,2,2,3,3,4,5,6,7,8,8,11,12,13,14,15,17,21,22,28

2. Count the total number of transactions;(T)= 20.

3. Calculate  Position (P) = (90/100) * T = 18;

4. Position 18 contains the 90th percentile value(V) =21;.

Simple Explanation :

         90% Response Time (RT) is the one factor we should always look in  once the analysis report gets generated to calculate the 90% RT.

•    Sort the transaction RT by their values.
•    Remove the top 10% instances
•    The higher value left is the 90% RT.

Ex:  

Consider we’ve a Script with transaction name “Trans(Ti)-testing” and there are 10 instances of this transaction i.e we run this transaction for 10 times.

•     Values of transaction 10 instances are;

         T1    T2    T3   T4  T5   T6   T7   T8   T9  T10

3

5

1

3

9

6

7

2

4

5

                     Sec

•     Sort them by their values

         T3    T8   T1   T4    T9   T2   T10  T6   T7  T5

1

2

3

3

4

5

5

6

7

9

                Sec

•     Remove the top 10% value i.e here  9 sec (T5)

          T3    T8    T1   T4   T9   T2   T10  T6   T7    T5

1

2

3

3

4

5

5

6

7

9 Remove

   Here the 90% RT value is    7Sec (T7)