Chapter 2
Statistics in Practice
By Boundless
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An observational study is one in which no variables can be manipulated or controlled by the investigator.
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The Clofibrate Trial was a placebo-controlled study to determine the safety and effectiveness of drugs treating coronary heart disease in men.
A confounding variable is an extraneous variable in a statistical model that correlates with both the dependent variable and the independent variable.
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The Berkeley study is one of the best known real life examples of an experiment suffering from a confounding variable.
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The Salk polio vaccine field trial incorporated a double blind placebo control methodolgy to determine the effectiveness of the vaccine.
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Numerous studies have been conducted to examine the value of the portacaval shunt procedure, many using randomized controls.
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A scientific control is an observation designed to minimize the effects of variables other than the single independent variable.