Thread: Useless facts/knowledge

Originally Posted by edhewitt

I am confused, how can the average wait = the mean time between buses?

It's known as the waiting time paradox in certain circles.

It's got to do with the idea of the mean time between buses - it's just the average, so actual bus arrivals will vary: some will take less time, some will take more time. There's a higher chance of you arriving in one of these longer time periods than arriving in a shorter one, so your average waiting time is longer than what you'd expect it to be if the buses arrived at exactly 30 minute intervals. Of course, if you arrive at the bus stop at random and the buses come exactly every 30 minutes, your expected waiting time would be 15 minutes.

The poisson process bit is what makes the average waiting time equal to the average time between buses - in a Poisson process the variance equals the mean, which makes the math work out the way it does (mean wait = mean time between buses). More generally the average waiting time is longer than half the mean time between buses, how much longer depending on the variance of bus arrival times.

It doesn't have to be buses either, of course. Any old waiting time will do.

James.

Originally Posted by Jimbo

It doesn't have to be buses either, of course. Any old waiting time will do.

James.

What about waiting for Guffman?

Armadillos are not college educated. This is a well known fact.

Mount Fuji is 12,365 feet high. An easy way to always remember this is; there are 12 months in a year and 365 days thus 12,365

In 2009 Racine, Wisconsin, USA won the best tasting municipal water in the USA.

Yep, pumped right out of Lake Michigan.

That is not why we moved here.

Dave

A "fathom" is a unit of measure that is US 6ft or SI Metric 1.8m. The use of a fathom is nearly obsolete as any nautical chart or citation using it as a unit of length will convert it to SI metric prior to release to Navy or civilian sectors. Oddly enough people use "fathometers" as a depth finder gauge but the use of "fathoms" on such tools are usually found on more expensive models... but no one really uses it for "fathom" measurements and only US Hydrographers use it but again, convert it to SI Metric prior to release to Navy or public. Go figure.

Thus, a fathom is rather useless since it will be converted one way or another. I know so, I did nautical charting for a few years and had the honor of converting every piece of someone's hard work done at sea. Click the meter button next time you butt pirate!

Originally Posted by Logistics

A "fathom" is a unit of measure that is US 6ft or SI Metric 1.8m. The use of a fathom is nearly obsolete as any nautical chart or citation using it as a unit of length will convert it to SI metric prior to release to Navy or civilian sectors. Oddly enough people use "fathometers" as a depth finder gauge but the use of "fathoms" on such tools are usually found on more expensive models... but no one really uses it for "fathom" measurements and only US Hydrographers use it but again, convert it to SI Metric prior to release to Navy or public. Go figure.

Thus, a fathom is rather useless since it will be converted one way or another. I know so, I did nautical charting for a few years and had the honor of converting every piece of someone's hard work done at sea. Click the meter button next time you butt pirate!

The commercial fishing sector still uses fathoms all the time. For depths on charts and for the measurement of line as well. It is the standard unit within the industry.

Till 1970..old dictionary.

dis·crim·i·na·tion
1.an act or instance of discriminating, or of making a distinction.
2. the power of making fine distinctions; discriminating judgment: She chose the colors with great discrimination.
3. Archaic. something that serves to differentiate.

Archaic...no longer taught nor suggested:

con·se·quence
ˈkänsikwəns,-ˌkwens/
noun
plural noun: consequences

1.
a result or effect of an action or condition.
"many have been laid off from work as a consequence of the administration's policies"
synonyms: result, upshot, outcome, effect, repercussion, ramification, corollary, concomitant, aftermath, aftereffect;

~Richard

Originally Posted by Jimbo

It's known as the waiting time paradox in certain circles.

It's got to do with the idea of the mean time between buses - it's just the average, so actual bus arrivals will vary: some will take less time, some will take more time. There's a higher chance of you arriving in one of these longer time periods than arriving in a shorter one, so your average waiting time is longer than what you'd expect it to be if the buses arrived at exactly 30 minute intervals. Of course, if you arrive at the bus stop at random and the buses come exactly every 30 minutes, your expected waiting time would be 15 minutes.

The poisson process bit is what makes the average waiting time equal to the average time between buses - in a Poisson process the variance equals the mean, which makes the math work out the way it does (mean wait = mean time between buses). More generally the average waiting time is longer than half the mean time between buses, how much longer depending on the variance of bus arrival times.

It doesn't have to be buses either, of course. Any old waiting time will do.

James.

Thanks Jimbo,
I sort of understand it a bit now