Oka and uma: Difference between revisions

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At the end of the game, the [[scoring|raw scores]] are converted into an "end game score". This is most commonly referred as the plus-minus (+/-) score. The four end game scores are always set up to sum with zero.  However, due to rounding errors, it is possible for the scores to equal to 1 or -1.  In this case, the leader's or that of last place end game score is adjusted to ensure a zero sum.
At the end of the game, the [[scoring|raw scores]] are converted into an "end game score". This is most commonly referred as the plus-minus (+/-) score. The four end game scores are always set up to sum to zero.


==Oka and uma==
==Oka and Uma==
The '''oka''' {{kana|オカ}} 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.  At the end of the game, the oka is awarded to the winning player.
After the game ends, oka and uma are applied.


The '''uma''' {{kana|ウマ}} is the set point spread applied to the players at the end of the game. The typical point spread uses the format of {{uma|+A|+B|-B|-A}}, where A > B. Of course, the point spread does not necessarily have to follow that pattern, by which the spread does not need to be symmetric. In general, the point spread can be set to any value as long as the four numbers add up to zero. Point modifications may be used either to ease the conditions or increase the difficulty, particularly for tournament settings.
===Oka===
The '''oka''' {{kana|オカ}} can be thought of as an "ante". When oka is used, all players pay a set amount at the start of the game. At the end of the game, the sum is given to first place. This sum is known as the oka.
 
The oka always is the difference between the starting score and target score. If the start score is 25,000 and the target score is 30,000, the difference would be 5k. Thus, every player would pay 5,000 points. Then, first place would receive (5,000 x 4) points back, for an oka of 20,000. Overall, first place has a net gain of 15,000 points, and the others lose 5,000 points. (The oka value would be stated as 20,000.)
 
If oka is disabled, then even if a target score is set, no payments are made.
 
===Uma===
The '''uma''' {{kana|ウマ}} is a set bonus/penalty for ending the game at a certain placement. The typical point spread uses the format of {{uma|+A|+B|-B|-A}}, where 1st place receives A, 2nd receives B, 3rd loses B, and 4th loses A.
 
The uma does not have to be symmetric. For example, uma can be set to {{uma|+30|-5|-10|-15}} or {{uma|+15|-5|-5|-5}}. Uma usually adds up to 0, but technically does not have to. Modifications may be used to make the conditions easier or harder, namely in tournament settings.


==Procedure==
==Procedure==
[[Image:PlusMinus.png|thumb|240px|right|End game results with raw scores and uma scores]]
The end game score is calculated as follows:
The end game score is calculated as follows:
# Raw are taken at the end of the game, naturally ordered by the final point values.
# Take the raw scores from the end of the game.
# Note the start score and target score point difference, find the ''oka''.
# Subtract the target score from the final point values. (If no oka is used, subtract the starting score instead.)
# Subtract the target score from the final point values.
# Find the '''oka''' and add it to the winner.
# Add the ''oka'' to the winner.
# Divide by 1,000.
# Divide by 1,000.
# Round to the nearest integer. If the division result produces a digit of 0.5, then the number is rounded down.
# Round to the nearest integer. A result of 0.5 is rounded down, not up.
# Apply the ''uma'' spread, if any.
# Apply the ''uma'' spread.
# If the sum of all four does not equal to zero, then the winner's score is adjusted to produce a zero sum.
# If, due to rounding, the sum of all four does not equal to zero, then the winner's score is adjusted to produce a zero sum. This adjustment is usually +/- 1 at most. (Note: in some rules, the loser's score may be adjusted instead.)


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.
Formula:


  End score = ((Raw points + Oka - Target)/1000) + Uma
  End score = ((Raw points + Oka - Target)/1000) + Uma


===Shortcut===
===Shortcut===
[[Image:PlusMinus.png|thumb|240px|right|End game results with raw scores and uma scores]]
For a given value of oka and uma, the overall change between raw score and final score will be the same. Therefore, by finding the net change from oka/uma once, you can skip having to do the entire process over and over.
This short cut only applies to the distribution of {{uma}}. Using the procedure above, suppose all players unrealistically finish with 25,000 points each.  The target points is 30,000 as standard.
 
#Before playing, calculate <code>Final Score - (raw score / 1000)</code> for each place. Use dummy numbers for raw score.
#After finishing the game, find the raw score, round it to the nearest 1,000 (rounding 500 down), then divide by 1,000.
#Use the calculated values from #1 to quickly determine final scores.
 
For example, if all players ended with 25,000 points, oka = 20k, and uma = {{uma|+20|+10|-10|-20}}:


{{uma compare|
{{uma compare|
Line 29: Line 44:
|score1 = 25000
|score1 = 25000
|score2 = 25000  
|score2 = 25000  
|scpre3 = 25000
|score3 = 25000
|score4 = 25000
|score4 = 25000
<!--uma settings-->
<!--uma settings-->
Line 40: Line 55:
}}
}}


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 {{uma}} uma.
This means, for these oka/uma settings, 1st place final score is equal to <code>(rounded raw score/1000) + 10</code>, 2nd place final score is equal to <code>(rounded raw score/1000) - 20</code>, and so on. In other words: instead of having to calculate oka and uma every single time, when you are 1st with these settings, you can divide score by 1000, then add 10.


Just to show, the values in the image to the right are used:
Using the above picture as another example:


{{uma compare|
{{uma compare|
Line 48: Line 63:
|score1 = 35700
|score1 = 35700
|score2 = 32400  
|score2 = 32400  
|scpre3 = 22200
|score3 = 22200
|score4 = 9700
|score4 = 9700
<!--uma settings-->
<!--uma settings-->
Line 59: Line 74:
}}
}}


As a note, the values on the right hand column did not change as the corresponding raw scores differed.  So, to quickly determine the end score, it is simply the rounding of the player's score divided by 1000.  Then the values in the last column is applied according to placement to produce the end score.
First place received 35700 points, so their end score equals <code>(36000) / 1000 + 10</code> = 46, which is what what first place actually got.


===With different oka and uma===
===With different oka and uma===
Naturally, with different oka and uma settings, the numbers will work themselves out differently than the {{uma}} set up.
Naturally, with different oka and uma settings, the numbers will work themselves out differently than the {{uma}} set up.


With an uma of {{Uma|30|15|-15|-30}}:
{{uma compare|
{{uma compare|
<!--player scores-->
<!--player scores-->
Line 79: Line 95:
}}
}}


The same scores are used and applied with an uma of {{Uma|30|15|-15|-30}}. This time, the values in the last column are naturally different, as the uma values are different.
Obviously, the net change is different.
 
== Floating uma ==
[[Image:UmaFloat.png|right|250px|thumb|Floating uma reflected in [https://tenhou.net/0/?log=2024091508gm-000b-18940-c5de598b&tw=3 these scores].]]
'''Floating uma''', or sliding uma, is an alternate implementation of uma. When floating uma is used, the uma points will vary based on the number of players above/below the target score.
 
Floating uma is used so that every player above the target score has uma >= 0, while every player below the target has uma <= 0. Afterwards, the uma of 1st is increased / 4th is decreased so that the combined uma still totals 0. This makes end score calculation centered around the target score more so than just simple placement.
 
{| class="wikitable"
|-
! Above !! Below !! Uma sign
|-
| Two || Two || + / + / - / -
|-
| Three || One || + / + / 0 / -
|-
| One || Three || + / 0 / - / -
|}
 
For example, when using +15/+5/-5/-15 uma, the numbers would shift as follows:
 
{| class="wikitable"
|-
! Above !! Below !! Uma sign
|-
| Two || Two || 15 / 5 / -5 / -15
|-
| Three || One || 15 / 5 / 0 / -20
|-
| One || Three || 20 / 0 / -5 / -15
|}
 
In some rulesets, it is possible for all four players to fall below the target score. Under this setting, there is no extension into the South/West round if the target score is not met; uma is applied as if there were two above and two below the target score (even though nobody hit the target score).


== Tie-breaker ==
== Tie-breaker ==
[[Image:Tiedscores.png|thumb|240px|right|End game results with two players with the [http://tenhou.net/0/?log=2014011412gm-0009-7447-f4a2bbb5&tw=1 same raw scores].]]
[[Image:Tiedscores.png|thumb|240px|right|End game results with two players with the [http://tenhou.net/0/?log=2014011412gm-0009-7447-f4a2bbb5&tw=1 same raw scores].]]
In the event of tied scores at the end of a game, then the tie-breaker based on the initial [[Jikaze|wind seating]] (or the first hand) may applied. The player closest to the dealer position takes the higher position. Afterwards, the final score procedure takes into effect.  Even with tied scores, the player in the lower position will receive a lower uma score. Alternately, any oka and uma may be split evenly between the tied players, resulting in a shared placing. The specific ruleset in use determines how this is handled.
 
When scores are tied, there are two main variations to how it is handled:
* Ties are broken based on the initial [[Jikaze|wind seating]] (seats in the first hand). When scores are tied, the initial East player beats South beats West beats North.
* Tied players split oka/uma bonuses evenly. For example, with an uma of {{Uma|20|10|-10|-20}}, if two players tie for 3rd, they would pay (-10 + -20) / 2 = -15 each.
 
Which variation is used will depend on the ruleset.
 
== Competition formats ==
{{main|Multi hanchan format}}
 
For some competitions, the same four players play out two or more hanchan to settle a score.  This is due to one hanchan deemed as inadequate to settle a score between four players due to factors such as luck. Various tournaments and professional organizations use this format.


==External links==
==External links==

Latest revision as of 01:57, 19 October 2024

At the end of the game, the raw scores are converted into an "end game score". This is most commonly referred as the plus-minus (+/-) score. The four end game scores are always set up to sum to zero.

Oka and Uma

After the game ends, oka and uma are applied.

Oka

The oka 「オカ」 can be thought of as an "ante". When oka is used, all players pay a set amount at the start of the game. At the end of the game, the sum is given to first place. This sum is known as the oka.

The oka always is the difference between the starting score and target score. If the start score is 25,000 and the target score is 30,000, the difference would be 5k. Thus, every player would pay 5,000 points. Then, first place would receive (5,000 x 4) points back, for an oka of 20,000. Overall, first place has a net gain of 15,000 points, and the others lose 5,000 points. (The oka value would be stated as 20,000.)

If oka is disabled, then even if a target score is set, no payments are made.

Uma

The uma 「ウマ」 is a set bonus/penalty for ending the game at a certain placement. The typical point spread uses the format of 「+A / +B / -B / -A」, where 1st place receives A, 2nd receives B, 3rd loses B, and 4th loses A.

The uma does not have to be symmetric. For example, uma can be set to 「+30 / -5 / -10 / -15」 or 「+15 / -5 / -5 / -5」. Uma usually adds up to 0, but technically does not have to. Modifications may be used to make the conditions easier or harder, namely in tournament settings.

Procedure

End game results with raw scores and uma scores

The end game score is calculated as follows:

  1. Take the raw scores from the end of the game.
  2. Subtract the target score from the final point values. (If no oka is used, subtract the starting score instead.)
  3. Find the oka and add it to the winner.
  4. Divide by 1,000.
  5. Round to the nearest integer. A result of 0.5 is rounded down, not up.
  6. Apply the uma spread.
  7. If, due to rounding, the sum of all four does not equal to zero, then the winner's score is adjusted to produce a zero sum. This adjustment is usually +/- 1 at most. (Note: in some rules, the loser's score may be adjusted instead.)

Formula: 

End score = ((Raw points + Oka - Target)/1000) + Uma

Shortcut

For a given value of oka and uma, the overall change between raw score and final score will be the same. Therefore, by finding the net change from oka/uma once, you can skip having to do the entire process over and over.

  1. Before playing, calculate Final Score - (raw score / 1000) for each place. Use dummy numbers for raw score.
  2. After finishing the game, find the raw score, round it to the nearest 1,000 (rounding 500 down), then divide by 1,000.
  3. Use the calculated values from #1 to quickly determine final scores.

For example, if all players ended with 25,000 points, oka = 20k, and uma = 「+20 / +10 / -10 / -20」:

Raw score conversion Score comparison:
Uma 「20 / 10 / -10 / -20」
Raw scores Rounded to nearest 1000 Div by 1000 (A) End score (B) End score diff (B - A)
25000 25000 25 35 10
25000 25000 25 5 -20
25000 25000 25 -15 -40
25000 25000 25 -25 -50

This means, for these oka/uma settings, 1st place final score is equal to (rounded raw score/1000) + 10, 2nd place final score is equal to (rounded raw score/1000) - 20, and so on. In other words: instead of having to calculate oka and uma every single time, when you are 1st with these settings, you can divide score by 1000, then add 10.

Using the above picture as another example:

Raw score conversion Score comparison:
Uma 「20 / 10 / -10 / -20」
Raw scores Rounded to nearest 1000 Div by 1000 (A) End score (B) End score diff (B - A)
35700 36000 36 46 10
32400 32000 32 12 -20
22200 22000 22 -18 -40
9700 10000 10 -40 -50

First place received 35700 points, so their end score equals (36000) / 1000 + 10 = 46, which is what what first place actually got.

With different oka and uma

Naturally, with different oka and uma settings, the numbers will work themselves out differently than the 「+20 / +10 / -10 / -20」 set up.

With an uma of 「30 / 15 / -15 / -30」:

Raw score conversion Score comparison:
Uma 「30 / 15 / -15 / -30」
Raw scores Rounded to nearest 1000 Div by 1000 (A) End score (B) End score diff (B - A)
35700 36000 36 56 20
32400 32000 32 17 -15
30000 25000 25 -20 -45
9700 10000 10 -50 -60

Obviously, the net change is different.

Floating uma

Floating uma reflected in these scores.

Floating uma, or sliding uma, is an alternate implementation of uma. When floating uma is used, the uma points will vary based on the number of players above/below the target score.

Floating uma is used so that every player above the target score has uma >= 0, while every player below the target has uma <= 0. Afterwards, the uma of 1st is increased / 4th is decreased so that the combined uma still totals 0. This makes end score calculation centered around the target score more so than just simple placement.

Above Below Uma sign
Two Two + / + / - / -
Three One + / + / 0 / -
One Three + / 0 / - / -

For example, when using +15/+5/-5/-15 uma, the numbers would shift as follows:

Above Below Uma sign
Two Two 15 / 5 / -5 / -15
Three One 15 / 5 / 0 / -20
One Three 20 / 0 / -5 / -15

In some rulesets, it is possible for all four players to fall below the target score. Under this setting, there is no extension into the South/West round if the target score is not met; uma is applied as if there were two above and two below the target score (even though nobody hit the target score).

Tie-breaker

End game results with two players with the same raw scores.

When scores are tied, there are two main variations to how it is handled:

  • Ties are broken based on the initial wind seating (seats in the first hand). When scores are tied, the initial East player beats South beats West beats North.
  • Tied players split oka/uma bonuses evenly. For example, with an uma of 「20 / 10 / -10 / -20」, if two players tie for 3rd, they would pay (-10 + -20) / 2 = -15 each.

Which variation is used will depend on the ruleset.

Competition formats

Main article: Multi hanchan format

For some competitions, the same four players play out two or more hanchan to settle a score. This is due to one hanchan deemed as inadequate to settle a score between four players due to factors such as luck. Various tournaments and professional organizations use this format.

External links

Oka and uma in Japanese Wikipedia
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