The square root of the variance is called the

Research has shown that patients' expectations of treatment effectiveness are affected by what a treatment provider is wearing. A white lab coat tends to increase their expectation of effectiveness. Sandra, a research assistant, had no preconceived ideas about her research project, but by chance she wore a white lab coat when working with experimental Group 1, but jeans and a t-shirt when working with experimental Group 2. This created a confounding variable. This confounding variable was a _____

a) selection bias. b) experimenter bias. c) placebo effect. d) random effect.

Johnny has recurring periods of intense fear during which he thinks that he is having a heart attack. He trembles and has a rapid heart rate. These symptoms indicate:

a. panic attack. b. posttraumatic stress disorder. c. agoraphobia. d. generalized anxiety disorder.