Suggested answer to exercise: Confidence intervals for mean FEV1, 5

Question 2: How would you write the standard error of the mean FEV1 to three decimal places?

Suggested answer

Standard error of the mean is included in the output from Explore:

Statistic Std. Error
FEV1 (litre) Mean 4.0607 .08895
90% Confidence
Interval for Mean
Lower Bound 3.9119
Upper Bound 4.2095
5% Trimmed Mean 4.0561
Median 4.1000
Variance .451
Std. Deviation .67153
Minimum 2.85
Maximum 5.43
Range 2.58
Interquartile Range .99
Skewness .064 .316
Kurtosis -.857 .623

The standard error of the mean is given as .08895. To three decimal places this is 0.089 litres.

Note that I have included a leading zero as well as removing the last two digits and rounding up. This makes the number look better and is easier to read. I have also added the units.

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Last updated: 6 October, 2006.

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