The “luck” term refers to the probability of successfully mining a block. The ratio between the number of blocks actually mined daily to the theoretical number of existing blocks is called the “luck value”.
For example, according to the ratio between a mining pool's hashrate to the network’s total hashrate, let’s say theoretically that 10 blocks will be generated per day. If 12 blocks were successfully mined by a pool in a day, the luck value would be 120%; if 8 blocks were successfully mined by a pool in a day, the luck value would be 80%.
PPLNS: The Pay-Per-Last-N-Shares payment method pays miners only once a block has been successfully found. This method retroactively tallies how many shares a miner has contributed to the pool since a block has been found to determine the amount of payout. It discourages miners from hopping from pool to pool. Luck value has a significant impact on the PPLNS revenue mode.
PPS+: The Pay-Per-Shares-Plus payment method pays out via the Pay-Per-Share method and adds in transaction fees via the Pay-Per-Last-N-Shares method. Luck value affects commission rewards (bonus).
PPS: The Pay-Per-Share payment method pays miners for the amount of shares they contribute to the pool. The value of each share contributed is determined by the crypto asset’s current network difficulty and the number of total share contributions from miners and mining farms. Although payouts happen irregardless of a pool successfully finding a block, blocks will be successfully found in a statistically predictable manner by the pool depending on the total amount of hashing power (shares) contributed by miners and mining farms. This is a strategy that provides regular payments, eliminates the mining “luck” factor, and often allows miners immediate payouts. Luck value has no effect on PPS and the mining pool itself bears the risk of low luck values.