To create an assertion:

Click the object you want to assert. For example, to assert a load test, click it in the project tree:

Click the image to enlarge it.
The load test inspector will appear on the right. Click Add Assertion.

The Add Assertion dialog will appear.

In this dialog, specify the following values:

Group	Option	Description	Comment
	Name	Name of assertion	This name is used to identify the assertion and does not affect the asserted value.
General	Statistics	Statistics to assert	For a list of available assertions, see Statistics Reference.
General	Type	Statistics metric to assert	For a list of available assertions, see Metrics Reference.
Constraint	Minimum	The minimum assertion value	The assertion will trigger when the measured metric is below this value.
	Maximum	The maximum assertion value	The assertion will trigger when the measured metric is above this value.
	Stop test on failure	If selected, the test stops when the assertion triggers
Tolerance	Max errors	The maximum number of errors that may occur within the period specified by the Within Period option before the assertion triggers	0 indicates no limit.
Tolerance	Within period	The time period during which Max Errors errors must occur to trigger the assertion	0 indicates no limit.

Creating Assertions