In: Statistics and Probability
Antigen Titer A vaccine manufacturer analyzes a batch of product to check its titer. Immunologic analyses are imperfect, and repeated measurements on the same batch are expected to yield slightly different titers. Assume titer measurements vary according to normal distribution with mean µ or σ = 0.070. (The standard deviation is a characteristic of the assay.) Three measurements demonstrate titers of 7.40, 7.36, and 7.45. Calculate a 95% confidence interval for true concentration of the sample.
First we calculate sample mean,
We have, given that,
σ = 0.070
alpha = 0.05 ( Here σ is known so use z-test) From standard normal table
95% confidence interval for mean is
Hence, 95% confidence interval for true concentration of the sample is " (7.324121,7.482545) ".