# 95% CI vs Mean +/- sample standard deviation

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#### Cognizant

We collected n=8 sample data and calculated descriptive statistics such as mean, sample standard deviation, estimated population standard deviation and 95%CI's for mean. we compared 95% CI to the predicate 95% CI and made a decision whether our devices are significantly different or not...

We also wanted to update our user manuals... Which statistic would be more helpful to the users ...

95% CI or Mean +/- sample standard deviation... Or both serve the same purpose ... Please let me know your thoughts ...

#### Bev D

##### Heretical Statistician
Staff member
Super Moderator
A few clarifying questions will help us provide you a better answer: What was the purpose of the study? 8 units is a very small sample size for a point estimate of something...how were the samples selected. Or we're they created under specific conditions?

What is the purpose of the 'manual'?

I general: As you know, the confidence interval you calculated provides the precision of the estimate of the mean of the population from which you sampled. And the +/- 3 SD will provide a rough estimate of the spread of the individual values of the population. At this sample size the width of the confidence interval and +/- 3 SD will be very close in size...

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