Sections 3 Introduction to Experimental Design Definitions treatment

Definitions treatment – the property being studied treatment group – the group possessing the

Definitions continued confounding factors – properties other than the treatment that can influence a

observational study the researcher does not control which subjects are assigned to the treatment

controlled experiment the researcher can control which subjects are assigned to the treatment a

Types of studies cross-sectional study - different subjects are compared to one another at

A researcher is attempting to measure the effectiveness of a new drug that claims

1. ) Does the study depict a controlled experiment or an observational study? 2.

Determine whether the study depicts an observational study or a controlled experiment. 1. A

Determine whether the study depicts an observational study or a controlled experiment. 3. While

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Sections 3 Introduction to Experimental Design

Definitions treatment – the property being studied treatment group – the group possessing the property control group – the group not possessing the property

Definitions continued confounding factors – properties other than the treatment that can influence a study

observational study the researcher does not control which subjects are assigned to the treatment observations and measurements of individuals are conducted in a way that doesn’t change the variable being measured

controlled experiment the researcher can control which subjects are assigned to the treatment a treatment is deliberately imposed on individuals in order to observe a possible change in the variable being measured

Types of studies cross-sectional study - different subjects are compared to one another at the same point in time longitudinal study the same subjects are compared to themselves at different points in time

A researcher is attempting to measure the effectiveness of a new drug that claims to lessen the severity of heart attacks. Half of the study participants are given the drug and the remainder are given a placebo.

1. ) Does the study depict a controlled experiment or an observational study? 2. ) What is the treatment? 3. ) What is the treatment group? 4. ) What is the control group? 5. ) Name a confounding factor that could influence the study.

Determine whether the study depicts an observational study or a controlled experiment. 1. A study to determine whethere is a relationship between the rate of cancer and an individual’s proximity to hightension wires. 2. Rats with cancer are divided into two groups. One group receives 5 mg of an experimental drug that is thought to fight cancer, and the other receives 10 mg. After two years, the spread of cancer is measured.

Determine whether the study depicts an observational study or a controlled experiment. 3. While shopping, 200 people are asked toperform a taste test in which they drink from two unmarked cups. They are then asked which drink they prefer. 4. A survey is conducted asking 400 people, “Do you prefer Coke or Pepsi? ”