An aspect of betting that always intrigues, and puzzles, most punters is the actual impact of their bet on the totalisator odds. With bookmakers, a punter can see immediately if his bet affects the odds on display, because the bookie will 'twiddle the knob' to lower the price.

This happens with bookies when a punter places a sizeable bet in comparison with the rest of the betting. For instance, a punter walking up and putting \$1,000 or more on a horse is likely to knock off the available price. But how would a similar bet affect the TAB odds?

The West Australian TAB recently issued its own details about such bet to odds moves-and an interesting document it is, too. There are examples given, which can be worked out by glancing at the list of statistics published on this page.

Example: On a race where the win pool is \$1,000, how much will the win dividend be reduced if I put \$30 on a horse paying \$1.55?

Answer: Find \$1.55 in the dividend column. Currently there is \$267 of the \$1,000 pool invested on this starter. Add your \$30 to \$267 giving you \$297. The corresponding dividend is \$1.40. Your \$30 bet, then, has cut the price from \$1.55 for a 50c bet to \$1.40.

To calculate the provisional win dividends on a pool greater than \$1,000, follow these rules:

1. Divide the existing win investment pool by \$1,000 (eg \$50,000 divided by 1000 equals 50.
2. Divide your bet by 50 (eg \$50 divided by 50 equals 1).
3. If the provisional win dividend on your horse is currently \$4.50, find that in Column 3. There is \$90 of the \$1,000 pool invested on that starter.
4. Add your \$1 to \$90 equalling \$91. The corresponding dividend is \$4.45. Your investment of \$50 in a \$50,000 pool would change the provisional win dividend from \$4.50 to \$4.45.

Let's take another look at some examples: On a \$1,000 pool, you bet \$126 on a horse currently paying \$57.20.

Currently (see the chart) there is \$7 of the pool bet on this horse. Add your \$126 to it and you get \$133. You now look across to the nearest total to \$133-say \$134-and you'll see that your bet has slashed the horse's odds to \$3.05. But remember the pool is only \$1,000. If the pool had been, say, \$250,000, you would have seen the following arithmetic:

1. \$250,000 divided by 1,000 equals 250.
2. Divide your bet (\$126) by 250, which equals 0.54.
3. Your provisional win dividend was \$57.20, with \$7 of the \$1,000 pool invested on it. Add your \$0.54 to the \$7, and you find that your \$126 bet has moved the total bet only marginally, to \$7.54, which equals, according to the chart, say a little over \$50. Remember, your \$126 has been thrown into a massive \$250,000 win pool, so that's why the movement is so slight.

By Martin Dowling

PRACTICAL PUNTING - OCTOBER 1991