What is the threat to internal validity that involves physiological processes occurring within the participants that could account for any changes in their behavior

As of 2013, the world’s total population was about

Sailors went to special school to learn how to use the new technology that would them sail far distences. the school we know about was

Pj conducts an experimental study on the effects of soft music during high stakes science testing. he randomly assigns students at the school. in one condition he does not provide music for testing while in the other group he does provide the music. he administers a pretest at the beginning of the year and a posttest at the end of the year. pj’s design is best described as a: a.static group comparisonb. pretest-posttest control group designc.control-group-time-series designd. nonrandomized control-group pretest-posttest design