Confidence interval of a SD
Construct a Confidence Interval for the Standard Deviation
Although I always teach my graduate students how to construct (with (2) a confidence interval for the variance, I have never, until today (the 7th of November, 2010) actually needed to do so for research purposes. A doctoral student in Education needed to test the null hypothesis that the population variance in a variable is zero. Rather than go the usual route of computing (2) and obtaining a p from that test statistic (which I would need to by hand), I took the easy approach and found a web app that would construct the confidence interval for me. Since the student had reported the standard deviation rather than the variance, I used an app that calculates the CI for the standard deviation. The app is at . You simply enter the sample standard deviation and sample size and click “Calculate now.”
[pic]
Confidence interval of a SD
| |
| |
|Parameter |
| |
|Value |
| |
|SD |
| |
|0.8374800 |
| |
|SEM |
| |
|0.1341041 |
| |
|N |
| |
|39 |
| |
|90% CI of the SD |
| |
|0.7065819 to 1.0349190 |
| |
|95% CI of the SD |
| |
|0.6844291 to 1.0793275 |
| |
|99% CI of the SD |
| |
|0.6444107 to 1.1754711 |
| |
| |
|These results assume that you have randomly sampled data from a population that is distributed according to a Gaussian distribution. |
|Note that the confidence intervals are not symmetric around the SD. This makes sense. SD values must be greater than zero, so the |
|uncertainty for the upper confidence limit extends further than the lower limit. |
Return to Common Univariate and Bivariate Applications of the Chi-square Distribution
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related searches
- confidence interval calculator
- two sample confidence interval calculator
- 90 confidence interval calculator
- confidence interval calculator for population mean
- confidence interval chart
- upper and lower confidence interval calculator
- 95 percent confidence interval calculator
- confidence interval range calculator with p hat
- confidence interval of the mean calculator
- confidence interval limits calculator
- upper limit confidence interval calculator
- 95 confidence interval calculator