# Factoring manually

can anyone help me to understand the basics of factoring manually?

• Suppose you run a 7.5 table relay and share Mitchell movement with NS at table 1 missing and 8x3-board rounds (arrow switch last round). All the NS pairs will play 24 boards; all the EW pairs will play 21 boards. In a match-point pairs game there is no problem as scores are expressed as a percentage of the maximum possible - which is different for NS and EW pairs as they play different numbers of boards. However, if you run a XImps (or similar) game where the result from each board has no maximum or minimum you will need to correct for this. Multiply the total score (positive or negative) of the EW pairs by 24/21. This accounts for the missed opportunities for good or bad scores caused by sitting out one round. EBU Score certainly has an option to do this for you and should be used for all XImp games.

Peter

• There are examples in the White Book.

To be able to match point manually with factoring you first need to be able to match point from a frequency table.

The method to match point from a frequency table is to list the different results in order with their frequencies, and work from the bottom up:
1. the bottom score gets its frequency - 1
2. going up the table, the scores get : their frequency + previous frequency + previous match points
3. as a check, the top score + top frequency = overall top + 1

Example 10 tables, top 18, average 9

``````Result  Score   Freq  MP
3NT=      400    2    2+1+14 = 17
1NT+2     150    1    1+3+10 = 14
1NT+1    120    3    3+4+3 = 10
3NT-1    -50    4    4-1 = 3
``````

Check 17+2 = 18+1.
Also, total match points = 2 x 17 + 1 x 14 + 3 x 10 + 4 x 3 = 34 + 14 + 30 + 12 = 90 = tables x average

If there is a missing result, the frequencies are factored to give the expected number of results, and the match pointing is done based on the fractional frequencies.

Example 11 tables, 10 results, top 20, average 10. Frequencies factored by 11/10 = 1.1

``````Results  Score  Freq  Adj Freq  MP
3NT=      400    2      2.2    2.2+1.1+15.5 = 18.8
1NT+2     150    1      1.1    1.1+3.3+11.1 = 15.5
1NT+1     120    3      3.3    3.3+4.4+3.4 = 11.1
3NT-1     -50    4      4.4    4.4-1 = 3.4
``````

Check 18.8 + 2.2 = 20 + 1
Total match points = 2 x 18.8 + 1 x 15.5 + 3 x 11.1 + 4 x 3.4 = 37.6 + 15.5 + 33.3 + 13.6 = 100 = results x average