Windows

I've have a research to do based on a scenario but I don't have a good knowledge on the topic.

The scenario is as follow:
"Software projects have a reputation for delivering over cost, over time and failing to meet the user or client expectations. The IT department you are a project manager in is no exception. The team of over 40 seem to work hard but rarely satisfy either the demand for IT services or on new software developments. As an IT professional you find the situation frustrating as the systems function is currently overloaded and is under performing. Unfortunately, a culture of mistrust has built up between the business users and the IT service function."


Question:
One of the difficulties in deciding which projects to proceed with is that they can all be justified by company need. Describe and explain tools and techniques which would help select the software projects that best support the organisations strategic priorities. Justify the tools and techniques you select in terms of how they are appropriate for this given scenario.
Please state clearly any assumptions you make.


I've been made aware that I'll be needing to talk on "Pareto" & "Cause and Effect" as techniques based on the scenario.

Can someone help me on this?
Thanks