Applescript: Check Effective ppi of document

Hi

I'm creating a script to check if I have any lo-res images in my document, using effective ppi (Yes I know about preflight) and just pop up a message. However I'm stuck on checking the results the following is returning…

[applescript]

tell application "Adobe InDesign CS6"

          activate

          tell document 1

                    set minimumRes to 100

                    set theEffectiveRes to {}

                    set theLink to every link

                    repeat with x from 1 to count of theLink

                              set the end of theEffectiveRes to effective ppi of parent of link x

                    end repeat

                    -- Here I need to check theEffectiveRes for any entires below minimumRes and display a message

          end tell

end tell

log theEffectiveRes

[/applescript]

many thanks

Shane