This report shows the 85th, 90th,
and 95th percentile elapsed times for all users and the union of all
transactions in a run, as well as for the 10 slowest transactions
in a run.
The default percentiles in this report, 85, 90, and 95, are
sufficient for most purposes. However, if you are required to report
on a different percentile set, click to change the percentiles
in this report and in the Page Percentile report.
The Summary page
of this report has a graph with three bars, which represent the 85th
percentile, 90th percentile, and 95th percentile elapsed times for
all users and for all transactions in the run. For the 85th percentile
bar, 85% of all users achieved the indicated elapsed time or better.
For the 90th percentile bar, 90% of all users achieved the indicated
elapsed time or better. And for the 95% percentile bar, 95% of all
users achieved the indicated elapsed time or better.
The 85%,
90%, and 95% pages show the elapsed time percentiles of the 10 slowest
transactions in the run. For example, if you click the tab for the
85th percentile, and the total for a transaction is 110 (the total
is beneath each bar), you know that 85 percent of the elapsed times
for that transaction are less than or equal to 110 milliseconds (ms).
This
graph provides an overall idea of the elapsed times for each transaction.
For example, the Transaction report might indicate that a Login transaction
is one of the 10 slowest transactions. However, it is possible that
only one instance of the Login transaction was extremely slow while
the other instances of the Login transaction were within acceptable
range. The Transaction Percentile report shows which transactions
have slow elapsed time averages because they were slow in general,
not because a few elapsed times (out of many) were extremely slow.
The
table beneath the graph provides more detailed information for each
transaction:
- The minimum elapsed time for the run.
- The average elapsed time for the run.
- The standard deviation of the elapsed time. The
standard deviation tells you how tightly the data is grouped about
the mean. For example, System A and System B both have an average
elapsed time of 12 ms. However, this does not mean that the elapsed
times are similar. System A might have elapsed times of 11, 12, 13,
and 12 ms. System B might have elapsed times of 1, 20, 25, and 2.
Although the mean time is the same, the standard deviation of System
B is greater—and the elapsed time is more varied.
- The maximum elapsed time for the run.
- The 85th percentile for the run. That is, for this particular
transaction, 85% of the elapsed times were equal to or faster than
this time.
- The 90th percentile for the run. That is, for this particular
transaction, 90% of the elapsed times were equal to or faster than
this time.
- The 95th percentile for the run. That is, for this particular
transaction, 95% of the elapsed times were equal to or faster than
this time.
- The number of attempts in the run.