Tools › Statistics › Descriptive and Outliers › Data Summary and Outliers › Example
NIST e-Handbook 1.3.5.17.1: Grubbs' test on the Tietjen–Moore uranium data
| Tool | Data Summary and Outliers |
| Source | NIST/SEMATECH (2012). "Grubbs' Test for Outliers." e-Handbook of Statistical Methods. Section 1.3.5.17.1. |
| Level | Undergraduate |
Problem
Eight mass spectrometer measurements of uranium isotope ratios read 199.31, 199.53, 200.19, 200.82, 201.92, 201.95, 202.18 and 245.57. Is the largest value an outlier at the 5 % level?
Inputs to Enter
- One column of the eight values; outlier level α = 0.05
Answers
- G = 2.4687 against the one-tailed 5 % critical value 2.032 (page); the two-sided 5 % critical value is 2.1266; 245.57 is an outlier either way
- Iterated two-sided Grubbs flags one value and stops at the second step
- Skewness G1 2.80, excess kurtosis G2 7.88, Shapiro–Wilk W 0.485
Notes
Paste the eight values in place of the default columns.
More Examples for This Tool
- NIST e-Handbook 1.4.2.8.3: heat flow meter calibration data (ZARR13), summary and tests
- NIST e-Handbook 1.3.5.17.3: Rosner's generalized ESD test on 54 values
- Grubbs 1950: residuals of the semi-diameter of Venus (NIST 1.3.5.17.2)
- Shapiro and Wilk 1965: W test on the weights of eleven men
- Anscombe 1973: the quartet, four data sets with the same summary statistics