I'm working on an Android app where, at one point, the user is asked to input whether something helped. Their options are 'Yes', 'No' and 'Don't Know'; or they could choose to ignore it. This is for multiple 'somethings' over a date range. A summary view for a date range shows the percentage of 'Yes', 'No' and 'Don't Know' entered for each 'something'. I'm also showing the 'Overall Effectiveness' as the percentage of 'Yes' inputs, which I realise is incorrect. I am thinking of changing that to 'Yes' minus 'No', but that doesn't address the 'Don't Know' inputs. How would I handle the data so that 'Overall Effectiveness' represents all 3 data inputs? So, for a 'something' which has a 'Yes' of 25%, a 'No' of 25% and a 'Don't Know' of 50%, would that be an 'Overall Effectiveness' of 0% ? Or would the 'Don't Know' affect that figure at all? As an additional to that, what graph type, other that Pie, would best display all 3 data?