Understanding data from scientific research: Sometimes what you read in a scient
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Understanding data from scientific research: Sometimes what you read in a scientificpaper or article you may find terminology that is unfamiliar and even intimidating. But focus on the main idea. An example of this is the next excerpt from an article: The following data is from the 2009/2010 progress report published by the National cancer Institute. Many pesticides and their metabolic products (breakdown products) are present in the human tissues and are linked to cancer. Monitoring their levels in humans is routinely done in studies that are trying to understand the causes of cancer. DDT and chlordane are commonly found pesticides in our environment. These are very persistent (does not break down) chemicals that are around even after their production was stopped more than 30 years ago. These are carcinogenic chemicals. Out body cannot completely eliminate them, but often break them down only to a small extent. Concentration of metabolites (breakdown products) of these pesticides have correlation with the occurrence of cancer in populations. Pesticide levels in human metabolites were measured in a random sample of participants from the National Health and Nutrition Examination Survey (NHANES). The data showed that the concentration of DDT (and its metabolities) have risen in the period studied. Chlordane was measured in the three metabolites. Concentrations of a metabolite of chlordane, oxychlordane, have risen, and those of trans-nonachlor and heptachlor epoxide have declined from 1999-2002. Table 2. Blood (lipid-adjusted) concentration of DDT and chlordane, nanogram/gram (ng/g), 1999-2002. Source: National Report on Human Exposure to Environmental Chemicals, Centers for Disease Control and Prevention, 2005 The independent variable(s) in this study is/are _______ The dependent variable(s) in this study is/are _______ Proper sampling technique is critical in establishing the validity of a scientific study. Thoughts about sample collection: One of the first steps in designing a valid scientific study is getting a representative sample of the population being studied. For example if the study is supposed to answer people of all ages then the scientist designing the study needs to have the members of all age groups represented in the correct proportion. Based on this information you have, do you think this study that represents a true sampling of the general population? Explain?Explanation / Answer
Dependent variable is the variable in scientific setting that is being tested and measured.
An independent variable is a variable that is being changed or altered to see it's effect on dependent variable.
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