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Thinking about points

From: Léonie Watson <tink@tink.uk>
Date: Thu, 11 Jul 2019 17:29:07 +0100
To: Silver Task Force <public-silver@w3.org>
Message-ID: <c3952262-f9fd-8b15-2143-2b5e679d2990@tink.uk>

I've talked with JF more about his proposed points system, in particular 
about the part that worried me most on the call on Tuesday.

I'm going to try and share my thoughts with you. I make no claims about 
any of this being final, concrete, or even entirely thought through, and 
if I'm repeating anyone's ideas without realising - I'm sorry, and thank 

I was worried about the idea of prioritising requirements based on user 
impact, because it will put people from one group into competition with 
people from another.

Let's take two possible user needs/requirements:

Requirement 1:
"I want to be able to use headings to understand the hierarchy of content."

Requirement 2:
"I want to be able to understand the audio content of video."

I'm not suggesting these should be actual requirements, I'm just making 
them up for the purposes of this email.

If we say that requirement 1 is orientated towards blind people, it 
isn't critical, and assign it 10pts; then say requirement 2 is 
orientated towards Deaf people, it is critical, and assign it 20pts; it 
puts blind people and Deaf people into competition with each other, when 
it comes to the way authors choose to collect points.

This doesn't seem like a good thing, and as it turns out I don't think 
it was what John was proposing.

We then began walking through some ideas, one step at a time, and we 
started with the premise that all requirements are worth the same points 
to start with. Let's go with 10pts for want of anything else.

Note: I know this idea isn't knew!

We then thought about how to start differentiating between requirements, 
without making it a competition between different groups of people.

We decided to identify how many user groups benefit from the requirement 
being met. Requirement 1 arguably benefits blind people, people with low 
vision, and people with cognitive disabilities; requirement 2 benefits 
Deaf people and people with cognitive disabilities.

So requirement 1 is multiplied by 3 (making it worth 30pts), and 
requirement 2 is multiplied by 2 (making it worth 20pts).

Note: the multiplier is based on the number of user groups that are 
benefited, not the number of users, and this was a really important 
distinction for me as JF and I talked. If we make it about numbers of 
users, we re-introduce the competition between users problem, and as 
previously noted that seems like a bad idea.

We then considered how many requirements were likely to benefit only one 
user group. This is a question worth considering in more depth, but the 
example that came to mind as JF and I talked was this:

Requirement 3:
"I want to be able to disable flashing content before it begins."

This requirement benefits one user group - anyone who will be exposed to 
the risk of seizing when they see the content flash.

Using the model so far, requirement 3 would be worth 10pts because it 
benefits only one user group. That completely fails to recognise how 
critical this requirement is to people in that group though.

So we then thought about having different levels of criticality for each 
user group. Let's say:

1. Useful
2. Needed
3. Critical

We could bikeshed on the names, so again, I'm just making them up for 
the purposes of this email. Don't get too hung up on them just yet.

Requirement 1 is:

* Needed by blind people. That's a multiplier of 3 (1 for the user 
group, and 2 because it's "needed" by that user group).
* Useful to low vision people. That's a multiplier of 2 (1 for the user 
group, and 1 because it's "useful" to that group).
* useful too people with cognitive disabilities. That's a multiplier of 
2 (1 for the user group, and 1 because it's "useful" to that group).

Requirement 1 therefore has a total multiplier of 7 (if you add up all 
of the above), making it worth 70pts.

This still doesn't quite work as intended though, because requirement 3 
would be worth 40pts compared to requirement 1 at 70pts.

Requirement 3 is critical to people with Photo-Sensitive Epilepsy. This 
means it has a multiplier of 4 (1 for the user group, and 3 because it's 
"critical" to that group).

There are different ways we might solve this, and I'm really winging it 
at this point, but stick with me.

We could use a different points system for the criticality levels.

1. Useful
10. Needed.
150. Critical.

Maths is not my strong suit, so I'm sure many of you will take one look 
at this and shoot it down, but hopefully you get the idea.

We could add another criticality level, perhaps "Life-saving", that 
would only be used rarely, perhaps even only for this requirement.

Note: as I write this email, I realise that requirement 3 also benefits 
people with cognitive disabilities who find moving/flashing content a 

Perhaps it would be useful to look more closely at the following things:

* How might we identify the different user groups?
* How many requirements are beneficial to 1 user group, 2 user groups, 3 
user groups, and so on.

That information might help us figure out the maths with a bit more 
certainty, even if we only use a small sample of requirements initially.

That's as far as we got. As I said at the start, I make no claims as to 
the usefulness of any of it!


@LeonieWatson Carpe diem
Received on Thursday, 11 July 2019 16:29:36 UTC

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