Analyze trends

In the Trends page, you can view a list of all trends defined in the system.

In this topic:

Overview

Defining trends enables you to compare performance test run data (transactions and web resources) over several instances of a test run. This provides better visibility into your application's performance and helps you identify improvements or regressions. For each trend in the list, summary information is displayed to provide a high-level overview of the trend.

Methods of comparison

There are two methods for comparing test run measurements to identify performance trends. You can either compare to previous, or select a run as the baseline. By comparing the same measurement in more than one instance of a test run, you can identify whether its performance trend is improving or regressing.

Method	Description
Compare to Baseline	You select one performance test run and define it as the baseline. All measurements in the report are then compared to the measurements contained in the baseline.
Compare to Previous	All measurements in a performance test are compared to the measurements in the performance test run that immediately precedes it.

Note: The two comparison methods can yield substantially different results.
As shown in the table below, the average Transaction Response Time measurement is being trended from four performance test runs: 3, 4, 5, and 6.

Transaction response time (Compare to baseline)

Name	Type	Average run 3 [Base]	Average run 4	Average run 5	Average run 6
All	TRT	4.567	1.22 (-73.29%)	2.32 (-49.2%)	12.455 (+172.72%)
TRX_01	TRT	2.045	4.073 (+99.17%)	2.035 (-0.49%)	1.05 (-48.66%)
TRX_02	TRT	1.045	2.07 (+98.09%)	1.015 (-2.87%)	1.051 (+0.57%)
TRX_03	TRT	3.053	3.067 (+0.46%)	2.009 (-34.2%)	2.654 (-13.07%)
TRX_04	TRT	6.055	6.868 (+13.43%)	5.011 (-17.24%)	7.05 (+16.43%)

Run 3 has been defined as the baseline. The average transaction response times in the other performance test runs are compared only to run 3.

In run 3, the average transaction response time for TRX_01 was 2.045. The average transaction response time for the same transaction in run 5 was 2.035, representing a slightly faster response time and therefore a slight improvement in the performance of this measurement. The percentage difference between the two figures is displayed in brackets, in this case -0.49%.

However, if the Compare to Previous comparison method was selected, then the average transaction response time in run 5 would be compared to run 4 (because run 4 precedes it in the table), and not to run 3. The value for run 4 is 4.073, while for run 5 it is 2.035, a percentage difference of -50.04%.

Transaction Response Time (Compare to previous run)

Name	Type	Average run 3 [Base]	Average run 4	Average run 5	Average run 6
All	TRT	4.567	1.22 (-73,29%)	2.3 (+90.16%)	12.455 (+436.85%)
TRX_01	TRT	2.045	4.073 (+99.17%)	2.035 (-50.04%)	1.05 (-48.4%)
TRX_02	TRT	1.045	2.07 (+98.09%)	1.015 (-50.97%)	1.051 (+3.55%)
TRX_03	TRT	3.053	3.067 (+0.46%)	2.009 (-34.5%)	2.654 (+32.11%)
TRX_04	TRT	6.055	6.868 (+13.43%)	5.011 (-27.04%)	7.05 (+40.69%)

Using the same data, the two comparison methods yield different results. The Compare to Baseline method shows a slight improvement (-0.49%), while the Compare to Previous method shows a more significant improvement (-50.04%).

Add a new trend

You can create a new trend to view changes in performance test run data over time. For details, see Trend reports.