Confidence Intervals for the Difference Between Treatment Group Means

7 inches. Strictly, this is not a meaningful statement Even though we do not know what it is, the population mean does exist as a precise value, and precise values cannot meaningfully be associated with a probability. In strict terms, the Cl is a range of values that is likely to cover the true but unknown population mean (Campbell andMachin, 1999). 

4 Confidence Intervals for the Difference Between Treatment Group Means 

---