Pancreatic cancer survival. Whether a value is a parameter or a statistic often depends on how we state the research question. For example, suppose that we review all the pancreatic cancer cases in a specified region and find that in those cases where surgical resection was performed, the median survival time was 18 months.

(a) If we wish to use the number “18 months” to make a statement about the median survival time for cases in our region during the time interval of the study, would this number represent a parameter or a statistic?

(b) Now suppose we want to use this number to make a statement about the effect of surgical resection in other similar cases.
Would “18 months” now represent a parameter or a statistic?