There are numerous methods for evaluating the effectiveness of a presentation. It truly depends on the audience and the objective of your presentation.
To generalize, I'll say, there are four main areas. Then I'll mention 2 additional relevant considerations:
1) Did they like it - were they entertained? Did you keep their attention?
2) Did they learn it - were you clear and concise? Could they answer some main points aligned with your objective?
3) Could they use it - can they take what they learned from your presentation and present it to someone else? Could they apply what they heard or learned?
4) Did it matter - was it worth their time? Did you accomplish your presentation objective? How do you know?
Two additional important considerations:
1) Content - how was your content? Clear, concise, organized, interesting, compelling, colorful, persuasive?
2) Delivery - how were your nonverbals? Voice, intonation, use of filler words, eye contact, use of hands and other gestures, visuals, and many more.
We could break each of these areas into further detail but I hope this gets you started!
Good luck with your upcoming presentations!!
Kind Regards,
Joe
