Independent Intervening and Dependent Variables-OMG what a confusing concept!

I'm looking to find the independent, dependent and intervening variables of my study so I can develop some good research questions.  This chapter was rather confusing and mapping out the different variables was a bit difficult.  Here's what I've come up with so far, but are they right??

The purpose of my study is do identify the interventions and service delivery methods used in southeastern Pennsylvania School Districts to reduce SLP caseload numbers to provide effective treatment of communication disorders in the least restrictive environment.

Independent                             Intervening                                                             Dependent
caseload size                           pre-evaluation intervention tools                          actual intervention/service                        
                                                                                                                            delivery

# responsibilities                      time to deliver interventions                                 effectiveness of
                                                                                                                             intervention
                                 

collaboration/training               barriers to service delivery methods                     perspectives of            
                                                                                                                             collaborating staff