27.1 Introduction: Body temperatures

The average internal body temperature is commonly believed to be $\mu ={37.0}^{\circ }\text{C}$, a guideline based on data over 150 years old (Wunderlich 1868). More recently, researchers wanted to re-examine this claim (Mackowiak, Wasserman, and Levine 1992) to see if this benchmark is still appropriate.

In this example, a decision is sought about the value of the population mean body temperature $\mu$. The value of $\mu$ will never be known: the internal body temperature of every person alive would need to be measured… and even those not yet born.

The parameter is $\mu$, the population mean internal body temperature.

However, a sample of people can be taken to determine whether or not there is evidence that the population mean internal body temperature is still ${37.0}^{\circ }\text{C}$.

To make this decision, the decision-making process (Sect. 15.3) is used. Begin by assuming that $\mu ={37.0}^{\circ }\text{C}$ (as there is no evidence that this accepted standard is wrong), and then determine if the evidence supports this claim or not. The RQ could be stated as:

Is the population mean internal body temperature ${37.0}^{\circ }\text{C}$?