Dr. Bloedorn is a health psychologist who researches nutrition. She is curious as to whether a new drink additive will help people consume fewer calories during a meal. The drink additive is a white, odorless, tasteless powder that a person can add to any drink. She plans to collect a random sample of 50 overweight students on campus and measure the calories they eat during lunch, using a calorimeter. She plans to give this additive to the same participants to use at lunch a few days later and measure how many calories they eat (again, using the calorimeter).
Which of the following threats to internal validity will Dr. Bloedorn NOT be worried about?
a. Instrumentation
b. Attritionc. Historyd. Placebo effects

a. Instrumentation

Explanation:

Instrumentation can be explained as the tools or means through which the investigators tries or attempts to measure items of interest in the process of data collection. This can also be described as the process of constructing research tools or instruments such as interview and questionnaire, for gathering data on a study.

In this case, Dr Bloedorn readily have the participants that she will use for her research and a calorimeter which will be used to measure the calories of the participants, this means that she need not to worry about instrumentation, that is , all the tools she will use to carry out her research.

Answer is C. History

Refer below.

Explanation:

Dr. Bloedorn is a health psychologist who researches nutrition. She is curious as to whether a new drink additive will help people consume fewer calories during a meal. The drink additive is a white, odorless, tasteless powder that a person can add to any drink. She plans to collect a random sample of 50 overweight students on campus and measure the calories they eat during lunch, using a calorimeter. She plans to give this additive to the same participants to use at lunch a few days later and measure how many calories they eat (again, using the calorimeter).

Following threat to internal validity will Dr. Bloedorn NOT be worried about is: History.

Adolf Hitler hated the blacks. He considered them sub-human and that's why he called them beasts. He hated homosexuals and anything else he considered unnatural under the sun. He hated gypsies because they were believed to commit incest.