Correlation is one of the fundamental LoadRunner scripting skills; and LoadRunner novices are usually not very good at it (which is expected), but people who think they are LoadRunner experts are sometimes not very good at it either.
Mercury has done just about everything it can to remove the need for complicated correlation (correlation rules, the “scan script for correlations” option in VuGen, HTML mode recording, the Click and Script vuser type), but there will always be web applications that will require you to perform manual correlation when scripting.
Mercury’s training material kind of glosses over correlation, and makes it look overly easy – the correlation exercise from the training material never gives any of my students any problems; but if the training material were to include difficult exercises, it would be necessary to spend another day, and more people would be unable to complete the exercises.
I usually tell my students that they will encounter some much more difficult to correlate applications than the Mercury Tours website, and they will need to spend some time improving their manual correlation skills using WDiff .
This exercise should really test your correlation skills. Every problem (or something very similar) has been seen “in the wild” while I have been creating scripts for LoadRunner.
The Correlation exercise is available here.
Also, you should have a go at the previous scripting exercises: