Which data distribution is commonly assumed for exposure data in IH, justifying the use of the geometric mean?

Which data distribution is commonly assumed for exposure data in IH, justifying the use of the geometric mean?

• A. Normal distribution.
• B. Uniform distribution.
• C. Lognormal distribution.
• D. Bimodal distribution.

Answer: (C)

Exposure data in industrial hygiene are typically produced by many multiplying factors and span wide ranges, producing a right-skewed distribution. This pattern is well described by a lognormal distribution. When you take the logarithm of the data, the distribution tends to become approximately normal, and the central tendency in the original scale is best described by the geometric mean. The geometric mean is the exponentiated mean of the log-transformed values, and it is less influenced by very high exposures, effectively reflecting a typical exposure level (the median in a lognormal distribution). This is why the geometric mean is commonly used for exposure data. Normal distributions would imply symmetry and arithmetic means that don’t handle the skew well; a uniform or bimodal distribution doesn’t fit the typical spread and shape of exposure measurements.

Exposure data in industrial hygiene are typically produced by many multiplying factors and span wide ranges, producing a right-skewed distribution. This pattern is well described by a lognormal distribution. When you take the logarithm of the data, the distribution tends to become approximately normal, and the central tendency in the original scale is best described by the geometric mean. The geometric mean is the exponentiated mean of the log-transformed values, and it is less influenced by very high exposures, effectively reflecting a typical exposure level (the median in a lognormal distribution). This is why the geometric mean is commonly used for exposure data. Normal distributions would imply symmetry and arithmetic means that don’t handle the skew well; a uniform or bimodal distribution doesn’t fit the typical spread and shape of exposure measurements.