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This article focuses on a chi-square test procedure that would establish the reasonableness of assuming a dispersion and average service life selected by the Simulated Plant- Record (SPR) method of life analysis to be descriptive of the mortality characteristics of an industrial property plant account. Depreciation calculations for industrial property are in most instances based on estimates of the mortality characteristics of the items constituting the property. These estimates are derived from a statistical analysis of property mortality data and, because they relate to future use of the property, are necessarily tempered with managerial judgment. Ideally mortality data would provide complete age identification of current and previous retirement experience; each unit of property could be identified by date of installation and age at retirement. The SPR method is a trial and error procedure that attempts to duplicate the annual balances (or cumulative retirements) of a plant account by distributing the actual annual gross additions over time according to an assumed mortality distribution.

The author comments on the article "The Influence of Setup Time on Job Shop Performance," by J. K. Wilbrecht and W. B. Prescott, published in the December, 1969 issue. The author asserts that Wilbrecht and Prescott mischaracterized machine setup operations in job shops. The author explains that setting up manufacturing equipment for a new job may involve dismantling the old setup as well as setting up for a new job, so time for both aspects should be accounted for. Other times, the changeoever is simpler and faster. The author also suggests that other aspects of the article do not reflect real-world conditions.