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Test Yourself

True or False

Question 1

A CI quantifies sample variability.

Question 2

In a sample of data that is normally distributed the 97.5th centile is the same as the upper 95% confidence interval of the mean.

Question 3

The standard error of a sample mean allows us to calculate confidence intervals for the population mean.  

Question 4

The average crown rump length of 100 fetuses examined by ultrasound was 10cm with a standard deviation of 1cm. A 95% confidence interval for the mean is approximately 8 - 12cm.


State whether the following interpretations of a 95% CI are true or false.

Question 1

We are 95% confident that our sample statistic is in this interval.

Question 2

If we sample repeatedly, 95% of all sample estimates will be in this interval.

Question 3

There’s a 95% probability that the true parameter lies within this 95% CI

Question 4

The true population parameter will be in this interval 95% of the time.

Question 5

We are 95% confident that the confidence limits contain the true population value



Which CI is wider?