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:

Descriptives
			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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