ESS210B
Prof. Jin-Yi Yu
An Example
qIn an experiment, forty measurements of air temperature were made. The mean and standard deviation of the sample are:
q                              x = 18.41°C    and   s = 0.6283°C.
q
qQuestion 1:
q     Calculate the 95% confidence interval for the population mean for these data.
q    
qAnswer:
q     From the previous slid, we know the interval is: x ± Z95% * s / (N)0.5
q     Z95% = 1.96
q     Z95% * s / (N)0.5 = 1.96 * 0.6283°C / (40 )0.5 = 0.1947°C
q     The 95% confidence level for the population mean: 18.22°C ~ 18.60°C.