There's lots to work with in this Washington Post story, which reports on a study that polled married people about how they met their spouses.
According to the Post, the study contacted about 200,000 people via email, and about 20,000 of them responded to complete the online survey. There seem to be two main results of this survey.
First, the story reports that
More than a third of the selected respondents reported meeting their spouse online. About half of that third met through online dating; the rest met through other venues such as chat rooms, games and virtual worlds.
a) Can you use this result to support the frequency claim that about 1/3 of all married Americans have met online? Why or why not? What validities will be most important as you consider this frequency claim? What information do you need to know?
The second major result from this study appears to be the following:
The online marriages were durable. In fact, people who met online were slightly less likely to divorce and scored slightly higher on marital satisfaction.
b) What kind of claim is this conclusion making ? What are the variables in this claim?
c) Sketch a bar graph of the result that is being described.
d) Apparently, the authors of the study wondered if demographic factors such as income or ethnicity might have explained why online marriages were higher in satisfaction. According to the following paragraph, did they rule out such alternative explanations?
After controlling for demographic differences between the online and real-world daters, those differences remained statistically significant...
e) The journalist obtained a quote from another psychologist (Dr. Harry Reis), who also reacted to this association. The psychologist was quoted,
“They did control for demographic factors,” he said. “But they did not control for personality, mental health status, drug and alcohol use, history of domestic violence, and motivation to form a relationship.” All of these factors are known to affect marital outcomes, he said.
How could the authors of the study rule out factors such as "motivation to form a relationship" in a future study?
f) Because this study was covered widely in the press, it provides a chance to see how a variety of journalists covered the story. Which of the following headines seems most appropriate, given the design and results of the study?
a) For a frequency claim, you need to interrogate construct validity and external validity. First, you'd want to ask about how accurately the scientists measured whether pepole had met their spouse online. Second, you'd need to know if the sample of 20,000 is representative. This is a very large sample--much larger than a typical, randomly sampled telephone poll would use. So it's important to ask whether these 20,000 sampled respondents represent all married Americans before you can generalize the results to that larger population. Fortunately, you can read the published journal article online and find out the details of the sampling.
b) This is an association claim--the two variables are "whether or not you met your spouse online" and "level of marital satisfaction."
c) Your sketched bar graph would have categories for "how people met their spouse" on the x axis and "Marital satisfaction" on the y-axis.
d) Apparently, they used multiple regression to rule out those demographic factors as third variables.
e) Dr. Reis's idea could be tested by measuring some of these personality variables in a large sample, as well as asking people how happy their marriages are and whether or not they met online. Regression analyses could control for the personality variables and see if there is still a relationship between meeting online and having a more happy marriage.
f) Of these, the third headline seems best. For one, it captures the correlational nature of the study (this headline makes an association claim, while the first two make a causal claim). It also gets the results right. The fourth headline is also an association claim, but in fact the study found that online marriages were a little more happy, so the fourth headline doesn't depict the results accurately.