NEGDs Are Especially Susceptible to the Threat of Differential Selection

question 3

Multiple Choice

NEGDs are especially susceptible to the threat of differential selection. Which of these is the most unlikely cause?

• A) There were errors in the baseline data collection for the communities.
• B) A historical effect took place that affected the intervention.
• C) The chosen communities were not similar enough.
• D) The investigator had adjusted for differences between the two communities.

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Definitions:

Washing Detergent

A chemical substance used to break up and remove dirt and grease from fabrics, commonly in the form of powder or liquid.

Calcium Nitrate

An inorganic compound used as a nitrogen fertilizer in agriculture and also in waste water pre-conditioning for odor emission prevention.

Atoms

The basic units of matter, consisting of a nucleus surrounded by electrons.

Nitrogen

A colorless, odorless, nonmetallic element that makes up about 78% of the Earth's atmosphere and is a constituent of all living tissues.