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In general terms, a confidence interval is a range of numbers which
are calculated so that the true populations mean lies within this
range with a particular degree of certainty.
The certainty in which a population mean lies within the range is
typically expressed as 95% confidence interval, or a 99% confidence
interval. As you add more certainty the width of the interval will
increase.
You should remember that a confidence interval is not interpreted
as a probability. That is to say a 95% confidence interval should
not be interpreted by saying there is a 95% probability that the
true population mean lies within the calculated range. The true
interpretation of a confidence interval is that 95% of confidence
intervals calculated from this population will contain the true
population mean. |
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