at load factor of / successful search takes comparisons and an unsuccessful search takes at load factor of / the numbers are and at higher load factors the numbers become very large the moralas you can seeis that the load factor must be kept under / and preferably under / on the other handthe lower the load factorthe more memory is needed for given amount of data the optimum load factor in particular situation depends on the tradeoff between memory efficiencywhich decreases with lower load factorsand speedwhich increases quadratic probing and double hashing quadratic probing and double hashing share their performance equations these indicate modest superiority over linear probing for successful searchthe formula (again from knuthis -log ( -loadfactorloadfactor for an unsuccessful search it is ( -loadfactorfigure shows graphs of these formulas at load factor of successful and unsuccessful searches both require an average of two probes at / load factorthe numbers are and and at they're and thus somewhat higher load factors can be tolerated for quadratic probing and double hashing than for linear probing