Jmeter Learning (7) Correct Understanding of 90% line in aggregate reports

90% the correct meaning of the line parameter: 

 

Although there is a certain truth in my understanding above, it is obviously wrong. Let's see what jmeter says on its official website?

90% line-90% of the samples took no more than this time. The remaining samples at least as long as this.

"90% of the samples do not exceed this time, and the remaining samples only need this ." (Translated by Google)

I didn't quite understand what it meant. So, click to explain in detail.

90% line (90 th percentile) is the value below which 90% of the samples fall. the remaining samples too at least as long as the value. this is a standard statistical measure. see, for example: percentile entry at Wikipedia.

The English is too bad and I still don't understand what it means, but I am prompted to use Wikipedia to check what is a percentile.

 

Percentile:

Statistical Terminology. If a group of data is sorted from big to small and the corresponding cumulative percentile is calculated, the value of the data corresponding to a one hundred-bit value is called the percentile of the one hundred-bit value. Can be expressed as: A group of n observations are arranged by numerical values, for example, the value at the position of P % is called the P percentile.

The median value is 50th percentile.

The 25th percentile is also known as the first quartile, expressed in Q1; the 50th percentile is also known as the second quartile, expressed in Q2; the third quartile (third quartile) is the 75th percentile, which is expressed in Q3. If the percentile p is a decimal number, it can be a complete integer.

Quantile is a measure of the location of a data, but it is not necessarily a central location. The percentile provides information about how each data item distributes between the minimum and maximum values. For data that does not have a large number of duplicates, the p percentile divides it into two parts. The values of data items about P % are smaller than the P percentile, while those of data items about (-p) % are larger than the P percentile. For the P percentile, the strict definition is as follows.

The percentile p is such a value, which causes the data items with at least P % to be smaller than or equal to this value, and at least (100-p) % to be greater than or equal to this value.

The admission exam scores of higher education institutions are often reported in percentages. For example, assume that the original score of a candidate in the language section of the entrance exam is 54. Compared with other students taking the same test, it is not easy to know how their scores are. However, if the original score of 54 is exactly 70th percentile, we can know that about 70% of students have lower scores than him, and about 30% of students have higher scores than him.

 

In fact, this is the final example of the examinee's score, which makes me suddenly understand.

 

Suppose:

There are 10:

Sort the values of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 in ascending order.

Calculate its 90% percentile, that is, the number of 9th is exactly 9, so his 90% line is 9.

Number of other groups:

2, 2.1, 2.5, 3, 3.4, 3.4, 4, 4, 4, 5, 5, 5, 5.9, 5.91, 6.8, 8, 12, 24, 24.1 sort them in ascending order.

Ask for its 90% percentile. Is the number of 18th 12, and his 90% line is 12.

 

90% line

Sort the number of a group from small to large and find its 90% number (if it is 12), then the number of 90% in this array will be less than or equal to 12.

The response time used for performance testing will also be meaningful, that is, the response time of 90% users will not exceed 12 seconds.

Jmeter Learning (7) Correct Understanding of 90% line in aggregate reports