Because low scores should indicate a Mexican cultural orientation, these results helped to establish the validity of the test. The assumptions required are that the data are a simple random sample from a normally distributed population. The detector readings were as follows. The distribution is somewhat skewed to the right, but not strongly enough to forbid use of the t procedures. Manufacturers also wish to be able to make claims about the variability of the radon detectors.
Gas chromatography is a sensitive technique used by chemists to measure small amounts of compounds.
The response of a gas chromatograph is calibrated by repeatedly testing specimens containing a known amount of the compound to be measured. Then explain to a chemist who knows no statistics what your margin of error means. The standard error is a measure of the sampling error, or variability in means from sample to sample. When the underlying data are normally distributed, then we know the distribution of sample mean, can assign a probability, or confidence level to a margin of error by taking the appropriate multiple of the standard error. Large trees growing near power lines can cause power failures during storms when their branches fall on the lines.