Just as minutes of meetings record decisions made, they should be reviewed later to see whether those decisions were the right ones.

Let us say immediately that there has to be a "policy of no blame" here. You will make mistakes - but don't make the biggest mistake of all, which is to make the same mistake twice. If you ordered too many burgers can you tell how many you bought, at what cost and can you suggest how many ought to be bought next time?
Some of this process is mentioned in Chapter 4 on Finance but it's worth repeating the use to which a spreadsheet can be put here. If you aren't into spreadsheets, then a simple list is quite good enough so long as it's based on information accurately collected.

You'll need a shopping list (see appendix vi) based on your needs. After the event do a stock check, list what's left over, ask everyone what they wanted more of and then amend the shopping list ready for next time. Use bills to check that what was bought actually matches the list.

Produce the shopping list as soon as the Feast is finished and you have the best chance of having an accurate list for next year.

A stock check is an essential at the end of the Feast. You're bound to have something left over and that's the only way you can tell what has been bought and sold. Don't forget to allow for extra goods which were sold at a discount at the end of the day; these won't show on a simple stock check but should be counted when calculating your shopping list.

Life becomes much more complex if you are holding several events because you should have a separate stock check after each event, but it is difficult to hold a cumulative stock check especially with new deliveries coming in.

Sometimes it's just best to ask the people on the bar how much they think has been used and try to correlate it with remaining numbers of glasses plus dipstick tests on the beer barrels. I think every little helps in trying to estimate usage because the aim is to provide the right amount next time.

Recording of goods in and out is always going to be difficult unless a single person is responsible for this. Having said that, in the heat of the moment all sorts of things happen when there is pressure to supply customers and sticking to the rules can come low on your priorities. The last thing you want is a pedant who slows you down by counting every item. Do the best you can.

Analysis

Analysis of the figures can take many forms. Aim to keep costs down, revenues up, payments before the event kept to a minimum. Keep waste down and sell everything you can. If you can do all this you are a genius. If you can move towards it then you've done well. Use the figures to inform you for next time, so you have nothing left over that you can't sell, so you have the optimum profit margin. It's a business.

Spreadsheets and graphs can reveal all sorts of patterns you'd otherwise miss, but the man on the bar can tell you just as clearly that next time you need more half pint glasses, fewer barrels and more returnable cans. The folks on the barbecue can tell you sausages are more popular than burgers but take longer to cook and should be started earlier.