Editing Likelihood principle (section)

===The voltmeter story===
An argument in favor of the likelihood principle is given by Edwards in his book ''Likelihood''. He cites the following story from J.W.&nbsp;Pratt, slightly condensed here. Note that the likelihood function depends only on what actually happened, and not on what ''could'' have happened.

: An engineer draws a random sample of electron tubes and measures their voltages. The measurements range from 75 to 99&nbsp;Volts. A statistician computes the sample mean and a confidence interval for the true mean. Later the statistician discovers that the voltmeter reads only as far as 100&nbsp;Volts, so technically, the population appears to be “''[[Censoring (statistics)|censored]]''”. If the statistician is orthodox this necessitates a new analysis.

: However, the engineer says he has another meter reading to 1000&nbsp;Volts, which he would have used if any voltage had been over 100. This is a relief to the statistician, because it means the population was effectively uncensored after all. But later, the statistician discovers that the second meter had not been working when the measurements were taken. The engineer informs the statistician that he would not have held up the original measurements until the second meter was fixed, and the statistician informs him that new measurements are required. The engineer is astounded. “''Next you'll be asking about my oscilloscope!''”

;Throwback to ''Example&nbsp;2'' in the prior section:
This story can be translated to Adam's stopping rule above, as follows: Adam stopped immediately after 3&nbsp;successes, because his boss Bill had instructed him to do so. After the publication of the statistical analysis by Bill, Adam realizes that he has missed a later instruction from Bill to instead conduct 12&nbsp;trials, and that Bill's paper is based on this second instruction. Adam is very glad that he got his 3&nbsp;successes after exactly 12&nbsp;trials, and explains to his friend Charlotte that by coincidence he executed the second instruction. Later, Adam is astonished to hear about Charlotte's letter, explaining that ''now'' the result is significant.