How do I interpret the measurements (Source, Value, Factor, Avg, Count, Min, Max, Sum and Std) in Performance Explorer?
The Value column is the exact value where the cursor is at that instance - represented by a crosshair on the graph. As the cursor is moved the Value will change.
Factor is the amount by which the actual value has been scaled to appear on the graph, if it is (1) this equals a real time value.
Source is the type of value being taken. Either Average, Count (total number of this measurement), Maximum, Minimum, Sum (total of all measurements added together) or STD (standard deviation of all measurements). Whether all of these value types are available will be dependent on the group of measurement being used e.g. Timer, Transaction, Summary, etc.
Interval represents over what period the value is calculated in seconds, for example, every 10-sec
The rest of the columns will be explained by this example:
Consider that there is a timer called GMO Products which represents Response Times in seconds, whose Source line on the graph is Average and is being measured at a 10 sec Interval.
This means that, for each 10 second interval, the response times for this timer are measured and then averaged.
Therefore if the test had lasted for a minute there would be six, 10-second intervals and consequently six average values.
The Count column would reflect this with a value of 6.
An average is taken for each time interval.
The Min column contains the lowest of these six Average values.
The Max column contains the highest of these six Average values.
The Avg column contains the average of these six Average values (Max value plus the Min value divided by 2)
The StdDev column is how much each Average value deviates from the overall average.
These general rules will apply for the other Source values, for example, if the Source is the Maximum values for the timer then the Max column is the highest value of these six maximum measurements. It is important to realize though that not every measurement will be relevant which explains why some columns contain no value.