This NBCNews online video explains a study whose claim is that "Your Instagram feed could predict if you'll suffer from depression."
This headline presents an association claim, because "predict" is an association claim verb. The headline is not claiming that your Instagram feed could make you depressed (or not). However, it is claiming that if we know something about your Instagram feed, we can predict whether you have symptoms of depression or not.
Take 2 minutes to watch the video now. As you watch, ask yourself, "what Instagram variable(s) predicted depression?"
a) What are the two variables in this claim? State them at the conceptual level.
b) How was each variable operationalized? Explain as carefully as you can. For each of these operationalizations, is it a measured variable or a manipulated variable?
c) What kind of study do we need to support an association claim. Did the researchers conduct that kind of study?
d) Sketch a graph or graphs of the study's results to the best of your ability. Will you sketch a bar graph or a scatterplot? Explain your choice. (Hint: The story mentions three variables, but the graphs you make will require you to focus on two variables at a time).
e) Can this study support the causal claim that "using Inkwell filters causes people to become depressed?" Why or why not? (apply the three causal criteria).
f) Has this study been published yet?
a) One variable is "way of using Instagram" and the other variable is "Level of depression."
b) The variable "Way of using Instagram" was operationalized via noting what kind of filter people used. There are several categories of filters, and it's not clear if the study categorized each filter separately, or if they quantified how "dark" or "color-free" the filter choice was for each photo. This was a measured variable.
Another variable the story mentions is the number of people in each person's Instagram photos. We can assume this was operationalized simply by counting the number of people in each photo. This is also a measured variable.
The "level of depression" variable was also measured; the video did not indicate how depression was operationalized. We can assume that depression was measured via a self-report survey such as the Beck Depression Inventory, but you'd have to check the original article to be sure. Around minute 0:32, the scientist in the interview implies that the participants were actually diagnosed with depression, so it's also possible that each person had an interview with a clinical psychologist.
c) A correlational study can support an association claim. This study was correlational because both of the variables were measured.
d) You might have made a scatterplot with "level of depression" on one axis and "number of people in the photo" on the other axis, with a scatterplot sloping down from left to right (a negative relationship).
If you assumed that the "filter" variable was categorical, you might have made a scatterplot with "level of depression" on the y axis and bars labeled "Valencia" and "Inkwell" on the x-axis. The bar for "Inkwell" should be associated with higher levels of depression.
e) This study does have covariance, such that people with higher levels of depression were more likely to use black and white filters. It's not clear if the study has temporal precedence, because we don't know if the filters and the depression score were collected at the same time or not. This study also does not meet internal validity, because correlational studies cannot control for all possible third variables. We might wonder if some outside variable, such as gender, is associated with both the filters people use (perhaps women use more black and white filters just because they try to be more artistic) and gender is also associated with levels of depression (women tend to have higher depression averages than men, overall). We'd want to see if the researchers controlled for such demographic variables in their statistical analyses.
Even though this study cannot support a causal claim, the finding is still interesting because it presents a possible behavioral predictor of depression.
f) The answer to this question is available at minute 0:20.