Home > Statistics Every Writer Should Know > The Stats Board > Discusssion
Confidence interval vs. standard deviation
Message posted by Jennifer (via 12.145.208.12) on December 21, 2001 at 2:49 PM (ET)
I know the mathematical calculations for both confidence interval and standard deviation. In basic terms, what is the relationship between them. I have a standard deviation of 1 min and a confidence interval of 16 seconds (with a mean of 2 min).
READERS RESPOND:
(In chronological order. Most recent at the bottom.)
Re: Confidence interval vs. standard deviation
Message posted by JG (via 128.8.23.133) on December 21, 2001 at 5:27 PM (ET)
You need sample size and confidence level to answer your question.
Re: Confidence interval vs. standard deviation
Message posted by Jennifer (via 12.145.208.12) on January 4, 2002 at 12:13 PM (ET)
I am looking for an explanation on the relationship between them not the calculation. Say my sample size is 100 and my confidence is 95%.
Re: Confidence interval vs. standard deviation
Message posted by JG (via 172.163.237.19) on January 5, 2002 at 3:16 AM (ET)
mean +/- SD*.196
Re: Confidence interval vs. standard deviation
Message posted by Jennifer (via 12.145.208.12) on January 9, 2002 at 9:16 AM (ET)
Okay .. Let me try again. With a mean of 2 and standard deviation of 1, two standard deviations from the mean accounts for 95% of my data ( between 0 and 4 minutes). My confidence interval at 95% is 2 +/- 0.196 (between 1.804 and 2.196). What is the relationship between 2 standard deviations away and confidence level of 95%??? in words ....
Re: Confidence interval vs. standard deviation
Message posted by Jack Tomsky (via 12.144.103.66) on January 9, 2002 at 1:20 PM (ET)
A confidence interval is calculated from the data. The interpretation in your example is that we are 95% confident that the true mean lies within the (random) confidence interval. A 95% confidence interval is also an inversion of hypothesis testing. It is the interval of all true means that would be accepted if tested at the 5% significance level. In other words, given the observed data, it is the set of true means that are statistically consistent with the data.
Your $5 contribution helps cover part the $500 annual cost of keeping this site online.
