Calculate 95 % Confidence Level for Mean, StandarDeviation

Assuming a Gaussian distribution it would be Mean ± 1.95996 StandarDeviation

dear friend
        we have properties of normal distribution  to find the different level of confidence between mean and standar devision.
     
In normal distribution we have equation for 68.26%confidence  between mean and standar deviation is
             mean ± standard deviation
and
equation for 95%confidence  between mean and standar deviation is
             mean ±1.96 standar deviation
and
 equation for 99.73%confidence  between mean and standar deviation is
             mean ±3 Standar deviation
           

  hopes it will works for u

 
   

>>mean ±1.96 standar deviation
>> mean ±3 Standar deviation
These are generally accepted formulae ?

i mean to say that , shall i directly use this formula in my applications
can u provide such values for different % confidence levels ..

They are for Gaussian distributions.

can u explin briefly what u want

You can if your application uses a Normal distribution.
Other values are
±0.67 sd  50%
±1.00 sd  68.26%
±1.65 sd  90%
±1.96 sd  95%
±2.00 sd  95.44%
±2.58 sd  99%
±3.00 sd  99.93%

here is another
If a statistic is normally distributed and the standard error of the statistic is known, then a confidence interval for that statistic can be computed as follows:
statistic ± (z) (σ )

where σ is the standard error of the statistic. For instance, the confidence interval for the mean is:
now u can use the formula by giving the value of z from the table of normal distribution .

or
 mean ± (z) (σ )
 

  asif

Sorry previous answers are not fully control

for alfa = 0,05
confidence is = 1,96 * standard deviation / sqrt (n)
where n is sample size.
this is formula used by Excel, it is also not exact, for better result you have to use t - kvantil, not
z - as Excel is using

x +/- 1,96 as previous answer says is a Range Size where is 95 % of values
Confidence interval is something different.

 Not exactly, it is range where with 95% probability that real mean
is in which (Real mean is mean from infinit values). So if you have high deviation you must to hevi high 1,96*deviation but it is not mean
that your confidence for mean is high.
if you have a distribution with high deviation, but you have enought measurment your confidence interval
can be low.

You can calculate also confidance for standard deviation, it is
for confidencer of stdev:
it is higher than
(n-1) Stdev*Stdev/(chi -kvadrat (n-1, 0.025)) and lower
(n-1) Stdev*Stdev/(chi -kvadrat (1-n-1,1- 0.025))

I can not write index, I hope zou understand.

Thi what previous answers say is colled

95 percentil (mean) range

here is another
If a statistic is normally distributed and the standard error of the statistic is known, then a confidence interval for that statistic can be computed as follows:
statistic ± (z) (standard deviation )
 
 

well shijusn

did u know about z-table and t-table in normal distribution

we can find any level of confidence by the help of these tables .

so post me back if u know about them then i will give u a detail infermation how to calculate any confidence interval between mean and standard deviation.


can u give me a sampl data also plze .it will helps me
i am waiting for this

HAVE GOOD TIME

ASIF SHARAZ

well shijusn

here we have Z table see the link
http://www.isixsigma.com/library/content/zdistribution.asp

for formula see this link

http://www.ruf.rice.edu/~lane/hyperstat/B9475.html

and how to apply this formula see the link

http://www.ruf.rice.edu/~lane/hyperstat/B7281.html

he solve here the problem for 95% cofidence interval for mean and standard deviation.

here is a option of "next page". He solve it in three pages see all the pages.By the help of this u can find any level of confidence interval for mean and standard deviation.

HAVE GOOD TIME

ASIF SHARAZ

hi
thanks for the comments
well, i am not an expert in maths.
i dont know much about those distributions.
it would be better if i get formula to find Confidence level for mean and sd
so that i can simply put values and get results.

is it different for different distributions ?

Hi Asif
that was an excellent comment
Thank u