Posted on Fri 27 May 2011 at 15:07 by Dan Connolly
In our Memberships Admin training on Wednesday the area that took up the most time was requirements. I tried to explain requirements in two ways, as descriptions and using venn diagrams (you can see some of the supporting images we used here) and while the descriptions were accessible to all I think I lost some of the audience when I started talking about logical operators and colouring in portions of overlapping circles on the whiteboard so I've decided to have another go at the diagrams I use to explain requirements.
(Once I've cleaned this up it'll be incorporated into the requirements page of the support section)
Every requirement starts off with a single group to include, some requirements might just be that single group (for example First Years). If you add that one requirement then that's what you get, a group that only First Years can be a member of.
Any subsequent rule we add to this requirement takes what we currently have a splits it in two. For example we want to look at all first years who are in a society. So we add our second requirement, membership of Societies Federation, and everyone in our current group (First Years) is either in the Societies Federation, or they're not. Simple as that. By adding another rule to our requirement we've split the group in two:
As you can see we can choose to 'Include' or 'Exclude' on our second rule, if we choose to include those people that meet the requirement we end up with First Years in Societies, if we choose to exclude it we end up with 'First Years not in Societies'. All we've done is taken what we had and split it in two.
In our example we wanted to include the group so we have First Years in Societies. Now say we want to refine this further, we want First Years in a Society and a Sports Club. All we need to do is add a new rule, Member of Athletic Union, and it will split our group in two once more:
And once again we choose whether we want the group that includes the AU or excludes the AU and that's how you build a requirement.
You may have noticed that we only used one letter option, 'A', this is because each letter is a single requirement, if you want to have a list that includes First Years in Clubs OR First Years in Societies then you have two possible requirements (the clue is any time you use the word OR when describing it you're adding a new requirement). So take each one in turn:
- 'A' - will be anyone who is a First Year and in a Society
- 'B' - will be anyone who is a First Year and in a Club
And each requirement you build you're just refining down your initial group, splitting it in two with each rule and choosing which half you'd like to keep.
Hopefully for those of you who got a little lost amongst my venn diagrams that's made things a little clearer!