9-hole score differentials in handicap

sjw

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I'm sure this has been done before but I'm wondering if anyone can explain the way 9-hole differentials are calculated when it comes into handicap. Presumably, they have to be converted to 18-hole differentials?

My course has a front 9 CR of 35 and a slope of 123. I shot a 44 which gives a differential of 8.3. I can work this much out through the usual calculation of 113/slope * (adj gross - CR), and it agrees with what I see on EG.

However, I have four differentials on my record so far - [18.4, 21.1, 8.3*, 18.4] - and I have an index of 16.4 (18.4-2)

I would have expected that the 8.3 would stand a chance of being the lowest differential. I'm sure it's not as simple as doubling it, but I can't work out a) why my handicap is still best-2 when I have four scores in and b) where the 8.3 fits in.

I am guessing that I don't have four scores in technically because they're not all 18-hole differentials?

Now, as for the 8.3, I think I've read something about the 9-hole to 18-hole conversion does something like assume that I scored nett par on the "back 9" or something. Seeing as I didn't have a handicap at the time, presumably this means that the differential is something mahoosive? If it is, and you can put in 6*9-hole cards for your initial handicap, are some people going to end up with really high indexes at first?

According to EG, for that 9-hole round, I had a course handicap of 27, so I'm doing something along the lines of

113/123 * (44 + 35 + 54 +1 - 70) = 58.8

Which seems crazy given I shot 9 over CR through 9...
 

jim8flog

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A 9-hole score is scaled up to an equivalent 18-hole Score Differential for
immediate use in the scoring record.
l A 9-hole score is scaled up to an equivalent 18-hole Score Differential by
adding net pars for the remaining holes plus one additional stroke (which is
applied to the first hole not played), or 17 points in Stableford format (see
 

wjemather

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I'm sure this has been done before but I'm wondering if anyone can explain the way 9-hole differentials are calculated when it comes into handicap. Presumably, they have to be converted to 18-hole differentials?

My course has a front 9 CR of 35 and a slope of 123. I shot a 44 which gives a differential of 8.3. I can work this much out through the usual calculation of 113/slope * (adj gross - CR), and it agrees with what I see on EG.

However, I have four differentials on my record so far - [18.4, 21.1, 8.3*, 18.4] - and I have an index of 16.4 (18.4-2)

I would have expected that the 8.3 would stand a chance of being the lowest differential. I'm sure it's not as simple as doubling it, but I can't work out a) why my handicap is still best-2 when I have four scores in and b) where the 8.3 fits in.

I am guessing that I don't have four scores in technically because they're not all 18-hole differentials?

Now, as for the 8.3, I think I've read something about the 9-hole to 18-hole conversion does something like assume that I scored nett par on the "back 9" or something. Seeing as I didn't have a handicap at the time, presumably this means that the differential is something mahoosive? If it is, and you can put in 6*9-hole cards for your initial handicap, are some people going to end up with really high indexes at first?

According to EG, for that 9-hole round, I had a course handicap of 27, so I'm doing something along the lines of

113/123 * (44 + 35 + 54 +1 - 70) = 58.8

Which seems crazy given I shot 9 over CR through 9...
While submitting the first 54-holes for initial handicap, 9-hole scores are paired to produce 18-hole score differentials. Any 9-hole score that is not matched before 54-holes have been entered is disregarded.

The initial handicap index is the lowest of the 3 18-hole score differentials minus a premium of 2.

Once scores from 54 holes have been submitted, 9-hole scores are scaled up to produce an 18-hole score differential by adding a second 9 hole score equivalent to 17 Stableford points over the same 9 holes.
 

sjw

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While submitting the first 54-holes for initial handicap, 9-hole scores are paired to produce 18-hole score differentials. Any 9-hole score that is not matched before 54-holes have been entered is disregarded.

The initial handicap index is the lowest of the 3 18-hole score differentials minus a premium of 2.

Once scores from 54 holes have been submitted, 9-hole scores are scaled up to produce an 18-hole score differential by adding a second 9 hole score equivalent to 17 Stableford points over the same 9 holes.
Ok thanks that makes a lot more sense. I wondered if it was a pairing thing. Case closed :)
 
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