Timeline for "Standard Deviation" of non-negative data
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| May 9, 2023 at 10:36 | review | Close votes | |||
| May 10, 2023 at 14:24 | |||||
| May 9, 2023 at 10:13 | comment | added | mkt | Does this answer your question? Can I use 'mean ± SD' for non-negative data when SD is higher than mean? | |
| Mar 10, 2014 at 22:37 | comment | added | user603 |
if, by positive the OP means asymetric and by Gaussian he means symmetric with square integrable tails then the OP has a point...
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| Dec 19, 2011 at 16:34 | comment | added | whuber♦ | @Dilip There are estimates of standard deviation, often called "pseudo SDs," that assume approximate normality. One is the IQR divided by 1.35. Another is half the difference between the 84th and 16th sample percentiles. A deeper question lurking here is whether an estimated SD is an appropriate way to measure variation for a strikingly non-normal distribution. (Another issue is the implicit, but incorrect, assumption that positive values cannot be adequately modeled by normal distributions.) | |
| Dec 19, 2011 at 16:33 | answer | added | King | timeline score: 3 | |
| Dec 19, 2011 at 16:12 | comment | added | Dilip Sarwate | This kind of comment, that standard deviation is defined only for normal distributions, or makes sense only for normal distributions, or the formula for standard deviation assumes that the data set is normally distributed, shows up so frequently here that it makes me wonder whether there is a commonly used textbook for a STAT 101 type course (or a popular web site that people visit frequently) which makes such claims or, more likely, makes statements that lead readers to make such unwarranted inferences. | |
| Dec 19, 2011 at 15:05 | answer | added | Brent Worden | timeline score: 5 | |
| Dec 19, 2011 at 14:46 | comment | added | whuber♦ | Because the standard deviation, as universally defined, makes no assumptions about normality--it's merely a sample statistic-- how does the SD that you "usually calculate" differ from it? | |
| Dec 19, 2011 at 13:46 | history | asked | Jeff Winterbourne | CC BY-SA 3.0 |