A New York Times Article Published on April 24, 2007

question 151

Multiple Choice

A New York Times article published on April 24, 2007, reported the research of Dr.Vallortigara, a neuroscientist at the University of Trieste, Italy.In this study, Dr.Vallortigara assessed whether a dog's tail wags in a preferred direction in response to positive as opposed to negative stimuli.First Dr.Vallortigara recruited 30 dogs that were family pets.While filming a dog's tail from above, he allowed the dog to view (through a slot in its cage) its owner, an unfamiliar human, a cat, and an unfamiliar dominant dog.The study found that dogs' tails wagged to the right for the owner and to the left for the unfamiliar dominant dog.What is the independent variable in this study?

• A) finding that dogs' tails went rightward for the owner and leftward for an unfamiliar dog
• B) the 30 dogs recruited for the study
• C) how far each dog wagged its tail to the right or left
• D) the type of visual stimulus provided to the dog

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Definitions:

Test Power

The probability that a statistical test will reject a false null hypothesis, a measure of a test’s effectiveness.

Sample Size

The number of observations or units included in a sample, which can influence the reliability and validity of statistical results.

Type II Error

An error resulting from failing to reject an incorrect null hypothesis.

Sample Size

The number of observations or elements chosen from a population for the purpose of statistical analysis.