Project L6

For the "Calculation of "1-2" Odds" spreadsheet:
The probabilities where X and Y are first in any order - how come the lower diagonal of the table is zero for all chances?

And:
If I had done the revised adjustment of data by hand (using the kennel girl's info), instead of by a formula (because I was running out of time, say), then how dangerous is this to do - marks-wise, how many marks (say) would be lost - enough to fail?

 

The diagonals are zero because a tie is not possible.

Since the kennel girls information comes later on in the day, hand adjusting of this information means most probably that you have hardcoded the position of the dog into your formulae. This is most probably not a good way of making your spreadsheet since it makes it difficult to adjust to other uses. Chances are it will cost you in time and marks.

Don't hardcode such stuff into your formulae as a matter of practice. Put the position in a cell and make your formulae refer to that cell. When the position changes just change the reference cell and you won't be out of time.

 

Hi,
The lower diagonal I meant was the lower bottom half of the diagonal, not just the diagonal alone - they are all zeroes compared to the upper diagonal half of the table. Why?

 

I suppose it's a matter of preference, although making the "lower half" all zero is sensible.

P(A and B are first two) = P(B and A are first two)

The way the sample solution excludes the double counting and only shows the unique entries. You can use the fact that they sum to 1 as a check. Alternatively you'll have everything twice so it sums to 2, not quite as neat and more cluttered.

Re hardcoding.
Almost certainly you'll have to expand your spreadsheet to handle the extra data, and it's far better (for reasons of checking, and using the model for something else later) that you don't hard code anything.

That being said, the spreadsheet doesn't carry too many marks and the audit trail and summary (where the marks are) depend on a working answer (of some sort, whether right or wrong)
So you might lose some audit marks, but if you can't do it otherwise, you can hard code it, finish your documents (and get marks to pass) and come back to fix it later.
Beware though - hardcoding sometimes takes longer and its easier to make errors, and harder for reviewer to follow.