Don't worry ... it's just a standard deviation

Of course, every time Cynthia and Gregory make the 8-block downtown trip to the Stinsons, it's going to take a different amount of time, depending on traffic and so on - even if it only varies by a minute or two.

Most of the time, the trip to the Stinsons' apartment would take between 10 minutes (in the middle of the night) and 45 minutes (in peak hour). Giving a range like that is similar to the concept of a margin of error or confidence interval (explained here).

So what's a standard deviation and what does it tell you? Well, it's not a comment on Gregory's behavior! Deviance as a term for abnormal behavior is an invention of the 1940s and '50s. Standard deviation (or SD) is a statistical term first used in 1894 by one of the key figures in modern statistics, Karl Pearson.

The standard deviation shows how far results are from the mean (or average). The standard deviation will be bigger when the numbers are more spread out, and smaller when there's not a huge amount of difference.

Lots of results will cluster within 1 standard deviation of the mean, and most will be within 2 standard deviations. Roughly like this:

95% of results are going to be within 2 standard deviations in either direction from the mean.You can read about how 95% (or 0.05) came to have this significance here. Statistical significance is explained here at Statistically Funny.

From the standard deviation, it's just a hop, skip, and jump to the standardized mean difference! More about that and an introduction to the mean generally here at Statistically Funny.

More about standard deviations here.

Comments

Austerity-A Fancy Word for Destitute.

The reason for this post is not for the folks who have been caught in the first wave of personal economic hard reality, but the next wave. Regardless of the optimism espoused by grinning leaders and sycophant press, we are entering the final stage of global economic collapse. It began in 2008 and was forestalled for five years with fudge putty, but the weight of global indebtedness cannot be propped any longer and the final crunch is imminent. Austerity measures herald the final throes. Indications of coming austerity. Austerity measures are the final last ditch effort, futile or not! Back in the day many of us old-timers went through periods of "hard-times". In retrospect I realize there is no comparison to yesteryear hard times and today's version. Back then, expectations were never very high for the working class, there were no sophisticated systems or conveniences anyway. In fact the difference between being "set" or not was about having treats or not. Si...

Terrifying Arctic methane levels

A peak methane level of 3026 ppb was recorded by the MetOp-B satellite at 469 mb on December 11, 2021 am. This follows a peak methane level of 3644 ppb recorded by the MetOp-B satellite at 367 mb on November 21, 2021, pm. A peak methane level of 2716 ppb was recorded by the MetOp-B satellite at 586 mb on December 11, 2021, pm, as above image shows. This image is possibly even more terrifying than the image at the top, as above image shows that at 586 mb, i.e. much closer to sea level, almost all methane shows up over sea, rather than over land, supporting the possibility of large methane eruptions from the seafloor, especially in the Arctic. Also, the image was recorded later than the image at the top with the 3026 ppb peak, indicating that even more methane may be on the way. This appears to be confirmed by the Copernicus forecast for December 12, 2021, 03 UTC, as illustrated by the image below, which shows methane at 500 hPa (equivalent to 500 mb). Furthermore, ...

Women and children overboard

It's the Catch-22 of clinical trials: to protect pregnant women and children from the risks of untested drugs....we don't test drugs adequately for them. In the last few decades , we've been more concerned about the harms of research than of inadequately tested treatments for everyone, in fact. But for "vulnerable populations," like pregnant women and children, the default was to exclude them. And just in case any women might be, or might become, pregnant, it was often easier just to exclude us all from trials. It got so bad, that by the late 1990s, the FDA realized regulations and more for pregnant women - and women generally - had to change. The NIH (National Institutes of Health) took action too. And so few drugs had enough safety and efficacy information for children that, even in official circles, children were being called "therapeutic orphans." Action began on that, too. There is still a long way to go. But this month there was a sign that ...

Humor4u

Search This Blog