Records should be adjusted for known sources of variation that are recurring and predictable. Which phrase best describes these sources?

• A. Recurring and predictable
• B. Random and unpredictable
• C. Irrelevant and minor
• D. Genetic only

Answer: (A)

When you adjust records for known sources of variation that recur, you’re accounting for systematic effects that consistently influence measurements. These sources come back under the same conditions, so their impact can be anticipated and removed from the data, improving the accuracy of estimates for the traits of interest. The best way to describe these sources is that they are recurring and predictable. Random and unpredictable variation cannot be forecast or adjusted in advance, making them different in nature; environmental or operational factors that recur (like batch, season, or location) are the ones you adjust for. Irrelevant and minor sources aren’t the focus of adjustment, and genetic only would ignore non-genetic, recurring influences that also affect the records.