Dr Wilson and Dr Storm restricted their study to white, Protestant teenagers, in order to eliminate confounding variables.

ECONOMIST: Human evolution

This was despite nearly identical power outputs in all four tests and efforts to control for possible confounding variables, such as the time of day.

ECONOMIST: Exercise and company

By a useful (though hardly unexpected) coincidence, all the businessmen were male and all were white, so there were no confounding variables of race or sex.

ECONOMIST: Physiognomy and success: Face value | The

There are many confounding variables, however, that affect the value of a business aircraft, and without considerable research it can be difficult to pinpoint the best aircraft for you.

FORBES: What's The Best Jet For You? (Part 3)

This latter pitch burnt us twice in the mid-2000s: Ivrea and Proprius both had inherited ongoing Phase 2s, both of which readout as completely uninterpretable due to protocol issues among other confounding variables.

FORBES: Lessons Learned: Reflections On Early Stage Biotech Venture Investing