tl;dr - Luck or hashrate at other pools makes no difference in the short term. The only thing that matters is the current hashrate and difficulty.
Do you care to throw some light on how Slush computes their pool luck then? Surely, network hash-rate is a factor (not mathematically speaking, but could also be!).
I know I'm not the one the question was pointed towards. However, I did mention this in several other posts in the past.
The hash rate has EVERYTHING to do with it. They would have to have a program that keeps up with the hourly total pool hash rate in the same way they have a program that computes the hourly hash rate of individual workers.
FIRST, lets say slush averaged 8 PH/s TOTAL hash rate from 00:01am at the beginning of the day till 24:00pm at the end of the day.
At present difficulty [35,002,482,026], that is approximately 5 hours, 13 minutes time for each block found (can vary greatly depending on our luck).
To be at 100% Luck for THAT 24 HOUR DAY [while averaging 8 PH/s for the entire day] we would need to find [24 hours divided by 5.21666667 hours] = 4.60063897 blocks for it to be 100% LUCK for THAT 24 hour period. Hence, you hardly ever see exactly 100% for 1 day luck. WHY? Cause we can't find 60% of a block. We can only find a "whole" block. You might see 100% for 7 day or 1 month, but not 1 day luck. That would be a rare occasion indeed.
Slush's "Luck" percentage for 1 day can also vary every hour IF they are computing this based on an "hourly" hash rate average.
The source I use to determine how many blocks on average that can be found for a "given" amount of hash rate is located at the following address:
http://www.bitcoinx.com/profit/ IF it does not load when you first navigate there, refresh the page and it should appear. You enter in the difficulty and the hash rate. No need to enter in the other data unless you are interested in your own profitability factor. The only thing we are concerned with is "How long it takes the pool to find a block on average for a given amount of hash rate of the pool."
The following answer was given for 8000 Th/s (8 Ph/s):
Difficulty 35,002,482,026.00
Mining Factor 100 0.00 USD/24h@100MHash/s as in these charts
Average generation time for a block (solo) 5 hours, 13 minutes (can vary greatly depending on your luck)Hardware break even 1 day
Net profit first time frame 3890503.64 USD
You can come up with these figures for ANY pool you desire by first entering in an approximate average hash rate of the pool. Then, if you like, you can determine the average payout for your personal hash rate at that pool by staying at the pool for 24 hours. Once you know your payout based on shares [considering if the hash rate is the same average as your previous calculation], you can multiply the average pay out by the average number of blocks found for each day. Then multiply that answer by 30 days and you have an average payout for a month for that pool.
Example:
[Slush] 4.60063897 blocks x .01452471 average shares with 4.67 TH/s = 0.06682295 BTC average each day. That would be 2.00468841 BTC in 30 days (1 month).