Oka and uma

Uma is the end game adjusted score. This is most commonly referred as the plus-minus (+/-) score. The four end game scores are set up to equal to zero. However, due to rounding errors, it is possible for the scores to equal to 1 or -1. In this case, the leader's end game score is adjusted to ensure a zero sum.

Oka

The oka is the point difference between the start score and the target score; and then it is multiplied by the number of players. In general, this can be viewed as the "ante". Typically, the start score and target score are 25,000 pts and 30,000 pts respectively. So, in this case the oka is 5,000 x 4.

Procedure

The end game score is calculated as follows:

1. Raw are taken at the end of the game, naturally ordered by the final point values.
2. Note the start score and target score point difference, find the oka.
3. Subtract the target score from the final point values.
4. Add the oka to the winner.
5. Divide by 1,000.
6. Round to the nearest integer. If the division result produces a digit of 0.5, then the number is rounded down.
7. Apply the uma spread, if any.
8. If the sum of all four does not equal to zero, then the winner's score is adjusted to produce a zero sum.

Due to rounding, the final values may not add up to zero. Therefore, it may become necessary to alter the winner's score. Usually, the difference is only +/- 1.

Shortcut

End game results with raw scores and uma scores

This short cut only applies to the distribution of (+20/+10/-10/-20). Using the procedure above, suppose all players unrealistically finish with 25,000 points each. The target points is 30,000 as standard.

End points	End pts rounded & Div by 1000	Oka	Minus target	Add oka	Div 1000	Rounded	+/-	End score	Diff. from 2nd column
25000	25	20000	-5000	15000	15	15	+20	35	+10
25000	25	0	-5000	-5000	-5	-5	+10	5	-20
25000	25	0	-5000	-5000	-5	-5	-10	-15	-40
25000	25	0	-5000	-5000	-5	-5	-20	-25	-50

As a shortcut, the adjustment can use the scores in the first column. Then the scores can be divided by 1000 and rounded. Finally, the values in the last column can be used to adjust for the final scores. Once again, this only works with the regular (+20/+10/-10/-20) uma.

Just to show, the values in the image to the right are used:

End points	End pts rounded & Div by 1000	Oka	Minus target	Add oka	Div 1000	Rounded	+/-	End score	Diff. from 2nd column
35700	36	20000	5700	25700	25.7	26	+20	+46	+10
32400	32	0	2400	2400	2.4	2	+10	+12	-20
22200	22	0	-7800	-7800	-7.8	-8	-10	-18	-40
9700	10	0	-20300	-20300	-20.3	-20	-20	-40	-50

If the original scores of (35700, 32400, 22200, 9700) were rounded and divided by 1000, the original scores would be converted to (36, 32, 22, 10). If (+10, -20, -40, -50) were added to the converted numbers, they would produce (46, 12, -18, -40).

External links

Barticle's guide