Drawing reasonable conclusions
• Understand that statistical methods are used to draw conclusions from data.
• Understand that the validity of data-based conclusions depends on the quality of the data and how the data were collected.
• Critique and evaluate data-based claims that appear in popular media.
Pick up any newspaper or magazine and you are likely to see statements that claim to be based on data. But were the data collected in a reasonable way? Are the conclusions drawn from the data reasonable and if so, to whom do they apply?
The goal of this section is to get students to think about conclusions based on data and to begin to think about aspects of study design that will be studied in more detail in the later sections of this unit. In this section, you can present students with statements for a recent newspaper or magazine, or you can use some of the ones that follow here. Encourage students to think about what data were collected and how the data were collected. Ask students if they have any reason to question the statement that was made. What additional information would they want to know before making a decision about the reasonableness of the claim?
You can ask students to bring in a headline or data-based claim that they find in a newspaper or online and use them as the basis for discussion on the second day of this section.
Sample data-based statements for discussion:
Women’s World (September 27, 2010): Eating cheese before going to bed will help you sleep better. Eating garlic prevents colds.
Associated Press (September 1, 2002): Vitamins found to prevent blocked arteries.
Women’s World (November 1, 2010): Strengthen your marriage with prayer.
Food Network Magazine (January 2012): People who push a shopping cart at a grocery store are less likely to purchase junk food that those who use a hand-held basket.
The Los Angeles Times (September 25, 2009): Spanking lowers a child’s IQ.
The following article might also be of interest: “Health Freaks on Trial: Duct Tape, Bull Semen and the Call of Television,” Significance, April 2014, Volume 11, Issue 2.
(the powerpoint that accompanies this can be found at http://www.amstat.org/education/stew/index.cfm)
WHAT: In this lesson, students consider an advertisement for a new cereal from Dodgycereals (the ad is in the powerpoint that accompanies the activity worksheet. You may wish to note that “dodgy” is used by the British to mean dishonest or unreliable). They critique the study design and evaluate whether claims made are appropriate. This also illustrates the process of using statistics to draw conclusions from data.
WHY: This lesson provides a good introduction to aspects of study design that should be considered when critiquing a study or evaluating a claim that is based on data.