Dyspraxia Awareness Week (by sarah)

It is Dyspraxia Awareness Week! And as I didn't know about it until yesterday I am trying to spread the word!

10th - 17th of October.

Firstly what is Dyspraxia I here the multitudes cry (ok well one or two of you anyway) - Dyspraxia is sort of Dyslexia of movement - obviously it is a lot more than this but that is the easy way of putting it.

There are other things associated with it such as loose joints and speech difficulties. I was 'diagnosed' with both Dyslexia and Dyspraxia at the beginning of my A'levels - there is a huge overlap between the two along with ADHD and Aspergers. I have posted on this before here.

I knew of the Dyslexia Association but not that there was a Dyspraxia Foundation.

Anyway I will probably do another few posts on this topic through out the week - you have been warned!

My Little Pedant (by sarah)

My Dad asked Jean if she knew fish had been alive on the Earth for millions of years, predating the dinosaurs.

Jean's response was - no they haven't!

Dad and Mum were like - yes they have been.

Jean got emphatic that they hadn't at which point I asked her why she thought that - Ferfer is wrong fish live in water not on earth.

Dad's face was a mask of amused disbelief. I explained that in this instance Earth meant the planet including the seas and oceans and not land. Jean thought it was silly we have two meanings for one word :/

Jean in Cheltenham (by sarah)

Going through the zillions of photos I have taken I found this photo of Jean in Cheltenham - Jean likes Chelt especially the bit with the Bull and Hare statu - It has a conquer tree and she doesn't have to hold hands with an adult and there are flowers!

It also generally means we are off to do something fun!

Eco-tricity (by sarah)

I realised from Alaric's post on heating that I had yet mentioned our new Electricity company Ecotricity. We decided to move to this local company as they sit with our green ethics better than any of the larger companies plus they are just up the road and they sent us stickers!

Old Papers (and maths!) (by alaric)

This weekend, I've been going through old papers and dealing with them. This involves sorting them into three categories:

1. To be shredded and turned into logs with our log maker
2. To be filed in the cabinet (with many subcategories corresponding to the files therein), and sorted by date where applicable
3. Demanding some action (which, for now, means putting them into my in-tray, rather than disrupting the activity in progress)

The magnitude and importance of this task is not to be underestimated - when we moved here I had a new baby, a very sick wife, and two jobs to deal with; unpacking and properly setting up my office never really happened, as opposed to setting up a desk and digging through boxes to find the things I needed to get started. So my once-pristine filing system was never quite established, and my "to file" tray grew fat with paperwork I needed to put somewhere. There was slow progress, of course; but then two years later the house flooded, so we had to rush a lot of furniture and stuff from downstairs up into the office, then pack a lot of stuff up and send it into storage while the house was repaired... and we weren't living in the house for nearly a full year, so more often than not I was working on my laptop from wherever I could get an Internet connection. Once again, my paperwork was in disarray.

But, three years on, we're finally catching up. I've gone through my filing cabinet and re-filed the mish-mash therein, then gone through my to-file tray and the various piles of papers dotted around the place, and dealt with them all. "To shred" has been by far the biggest category; as I write, Sarah is sitting feeding sheet after sheet into the shredder. And I've found a bunch of interestings that need further action.

For one of them in particular, the action is to write it up. Many years ago, I bought and read a book on statistics in order to refresh my memory, as I was working on a system for analysing the actions of large numbers of people. Now, I didn't enjoy statistics much when I was doing A-level maths, and reading the book reminded me why: I find the random-variable notation unnecessarily vague and confusing, and the various other notations used in statistics seem inconsistent to me.

I recall reading this book on a long bus journey (the bus from Tottenham Court Road to Gallows Corner in Romford, to be precise), and deciding to take matters into my own hand, and designing m own notation for statistics based on set theory. I like set theory and find it sensible and logical, so this was an obvious choice. I wrote my notation down on a sheet of paper, tucked it into the book, and took it home.

Many years later, I found the sheet of paper inside the book, and put it in my TODO pile, as I needed to take a second look at it and do something with it. This never happened. Until now.

So without further ado, here's the content of the sheet. It still needs more thinking about, but if I write it up into the computer now, this is more likely to happen than waiting for me to encounter this bit of paper again.

Let L be a multiset of real numbers.

• SUM(L) = sum of x, where x is an element of L.
• |L| = the number of elements in L.
• L(n) where 1 <= n <= |L| = nth largest element of L
• MIN(L) = L(1)
• MAX(L) = L(|L|)
• MEDIAN(L) = L(|L| / 2) if |L| is odd, (L(floor(|L| / 2)) + L(ceil(|L| / 2)))/2 otherwise
• SUM^2(L) = sum of x^2, where x is an element of L
• VAR(L) = SUM^2(L) - (SUM(L))^2 etc.
• L ~ D iff L is distributed as per D (D is a distribution as per normal stats notation)
• SRn(L) is a multiset of all possible sets of n random samples from L with replacement
• SWn(L) is a multiset of all possible sets of n random samples from L without replacement

Let L be a multiset of records (named tuples) of real numbers (a,b,c,...)

• La is a multiset of just the as
• Lab is a multiset of the products, a*b
• sigma(L) f(a,b,c) is the sum of f(a,b,c) across all the elements in L
• pi(L) f(a,b,c) is the product
• L ~ (D1, D2, ...) iff. La ~ D1 and Lb ~ D2 and so on
• cov(a,b)(L) = sigma(L) ab - M(La)*M(Lb)

...and there it ends!