In a research study to test a new drug on patients with brain cancer, patients were divided into 2 groups randomly. One group received the drug and the other group did not receive the drug. After 6 weeks, the measured results showed reduction in symptoms among the first group who received the drug. Is this an example of an observational study or experimental study? If it is an experiment, what is the controlled factor?

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Types of Bias

Statistics is the study of data collection, organization, analysis, interpretation, and presentation. Statistical bias is a characteristic of a statistical technique or its findings in which the expected value deviates from the actual root quantitative parameter being estimated. According to the actual definition of bias, it refers to the tendency of a statistic to overestimate or underestimate a parameter.