Penny Data Set
The data set available here contains masses for 100 circulating U. S. pennies. All pennies in these data sets were minted between 1962 and 1981, a period during which a penny’s composition […]
Statistics
Analysis of Pb in Biological and Environmental Samples
A paper by Yan, et. al. [Yan, X.-P.; Sperling, M.; Welz, B. Anal. Chem. 1999, 71, 4216-4222] describes a newly developed analytical method for the analysis of biological and environmental samples containing […]
Analysis of a Digital Pipet
Mechanical micropipets are commonly used to dispense small (μL) volumes of reagents. A recent “Application Note” [Am. Lab. June 1999] contains the following data for 50 replicate deliveries of a reagent using […]
Determination of Fat in a Snickers’ Bar
In a recent paper [J. Chem. Educ. 1997, 74, 1108-1111], Snow, Dunn and Patel describe the experimental determination of fat in a SnickersTM candy bar. The fat was removed by extraction with […]
Comparison of Glucometers
A glucometer is a portable device used to monitor glucose levels in blood. Of concern for users is repeatability between units of the same model, or between different models. The following data […]
Spike Recovery for Analysis of Ginkgolide
One concern in any analysis is the impact of the sample’s matrix. A method for an analyte that is known to work well in one matrix may yield problems when applied to […]
What is the Difference Between Repeatability, Reproducibility, Accuracy, and Precision?
In an editorial published in American Laboratory (November 2000), Ira S. Krull states that in “any science, then, one must present at the very outset evidence of repeatability, reproducibility, accuracy, and precision […]
NIST Statistics Problem
Have you ever wondered how atomic weights are determined? The National Institute of Standards and Technology (NIST) is one of several research organizations that seeks to make accurate measurements of this sort. […]
Anscombe Data Set for Linear Regression
The importance of visually examining a regression line relative to the data on which the regression is based is a point that cannot be overemphasized. The Anscombe data set, created by the […]