Archived posting to the Leica Users Group, 1997/09/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 09:28 PM 9/2/97 -0500, Eric Welch wrote: >At 01:48 PM 9/2/97 EDT, you wrote: >>you want to make claims based on statistics, get meaningful ones -- >>survey thousands of owners, or try to get the facts on repair rates >>from Leica service. > >Actually, for most populations, a sample of 400 is adequate. :-) > Actually, it depends on the overall frequency in the population of what you're trying to measure. If you're trying to measure something that has an overall frequency of about a half, then 400 samples give you pretty tight error bounds. If you're trying to measure something that has an overall frequency of 1/1000, then 400 samples give you pretty poor error bounds... but that wasn't the problem with this survey. Personally, I think that surveys like this one of M6 owners are worse than useless -- they're misleading because they're more likely to produce incorrect results than correct ones. Unhappy people are more likely to respond to such surveys with a complaint than satisfied people with a message saying "mine works fine."