Re:“You don't have a voltmeter. Do you have a potato?”
by unlikelymordant on Thursday November 24, 2022 @11:19PM
(#33739124)
Can you explain the story? I understand an oscilloscope is for looking at signals, but i dont understand the significance
Re:“You don't have a voltmeter. Do you have a potato?”
by fenomas on Thursday November 24, 2022 @11:34PM
(#33739206)
The context can be found here:
> https://en.wikipedia.org/wiki/Likelihood_principle#The_voltm...
Specifically if you read the "Example 2" section above that blurb, and then read the "throwback" bit at the end after the voltmeter story, it makes more sense.
Re:“You don't have a voltmeter. Do you have a potato?”
by quickthrower2 on Friday November 25, 2022 @12:45AM
(#33739624)
What is a good book for someone comfortable with maths (but very out of practice) to get up to speed on the topic. Not being scared of not understanding stuff and needing to learn prerequisites (so doesn’t need to be too easy). Because the wikipedia article isn’t really for learning but it does give a flavour. And it sounds fascinating, sort of like a monte hall problem to me.
Re:“You don't have a voltmeter. Do you have a potato?”
by whatshisface on Friday November 25, 2022 @12:20AM
(#33739490)
Oscilloscopes can also be used to measure voltages, often in excess of 100V, so in the spirit of those extremely unlikely "explanations" that show up in the explainxkcd tables, I offer this.
PS this story doesn't make sense because you can tell when a voltmeter is out of range.
Re:“You don't have a voltmeter. Do you have a potato?”
by aix1 on Friday November 25, 2022 @12:45AM
(#33739627)
> PS this story doesn't make sense because you can tell when a voltmeter is out of range.
It's also a bit sloppy with the bounds. To me, "reads only as far as 100" includes 100V, whereas the measured voltages only go as high as 99V.
Re:“You don't have a voltmeter. Do you have a potato?”
by whatshisface on Friday November 25, 2022 @01:07AM
(#33739742)
While we're complaining, you can't measure the "voltage" of an electron tube out of circuit.
Re:“You don't have a voltmeter. Do you have a potato?”
by ilyt on Friday November 25, 2022 @05:43AM
(#33741110)
Sure you can, just buy a SMU (source measurement unit, few multimeters cobbled together with 4 quadrant power supply)
Re:“You don't have a voltmeter. Do you have a potato?”
by YetAnotherNick on Friday November 25, 2022 @07:09AM
(#33741653)
I think the point is that the sample readings were in the range of voltmeter, but if some sample crossed 100V it would show as 100V in the voltmeter. So even though no sample crossed 100V, the data is clipped still.
Re:“You don't have a voltmeter. Do you have a potato?”
by whatshisface on Friday November 25, 2022 @01:51PM
(#33745561)
That's not good statistics - just because the precision of measurements falls off sharply at 100V doesn't mean that out-of-range readings aren't valid measurements.
Re:“You don't have a voltmeter. Do you have a potato?”
by YetAnotherNick on Friday November 25, 2022 @02:42PM
(#33746035)
Assume we got one out of range measurement out of 100. We can't say anything about variance of reading if we don't have any prior on variance ie using bayesian statistics. That's the joke that traditional statistician can't figure out the obvious thing.
Re:“You don't have a voltmeter. Do you have a potato?”
by charcircuit on Friday November 25, 2022 @03:30AM
(#33740415)
Why would the population be censored if the voltmeter never read anything above 100 volts?
>An engineer draws a random sample of electron tubes and measures their voltage. The measurements range from 75 to 99 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, so the population appears to be 'censored'. This necessitates a new analysis, if the statistician is orthodox. However, the engineer says he has another meter reading to 1000 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, the next day the engineer informs the statistician that this second meter was not working at the time of the measuring. The statistician ascertains that the engineer would not have held up the measurements until the meter was fixed, and informs him that new measurements are required. The engineer is astounded. "Next you'll be asking about my oscilloscope".