Change budget vs Change Tolerance

When I was a trainer I used to tell this story (which is true by the way) to illustrate the difference between change budget and tolerance

I went out with my girlfriend and I offered to buy her a dress. I said she could have £100 to spend with a tolerance of £20, but there was to be no change budget.

So she went out and found herself a dress (which looked very nice) for £80. Whilst she was shopping she found a nice pair of shoes for £30, which would have gone very nicely with the dress

Having found both these items she asked if it was OK that she could spend the money on both.

Being the gent I am I reminded her of what i said, she had £100 to spend with a tolerance of £20. She said “well in that case that’s fine I can get both.”

However I reminded her there was no change budget, so the pair of shoes constituted a change to the original requirement (a dress). The dress was fine as that was within tolerance (£100-£20=£80), so I would pay for that. As there was no change budget I wouldn’t pay for the shoes

As it was pointed out to me several times on the courses I delivered if the original requirement was an outfit then she could have had the dress and the shoes (and probably other accessories as well)

Obviously the moral of this story is don’t go shopping with me, or be clear on your requirements up front.