This story comes from the website studyfinds.org--a website that covers a wide range of scientific studies (and therefore a great place to practice critical reading of how journalists cover science news).

**The StudyFinds journalist describes** a newly-published Dutch study on body image and depression in teenage boys and girls. The result is an example of a moderator, so let's practice moderator reasoning.

Here is some of the journalist's description:

The study by researchers at Erasmus University in The Netherlands tracked 4,000 teenagers for several years. Researchers found that young men are a staggering 285 percent more likely to have a severe depressive episode if they were unhappy with their bodies as teens.

Their female counterparts were also affected, but were 84 percent more likely to suffer the same problems if they had been insecure about their appearance.

You might be wondering what it means to be "84 percent more likely" or "285 percent more likely?" These numbers seem huge. You should convert the percentage to a decimal (i.e., 0.84 or 2.85), and then multiply that times some baseline rate. So in the case of depression, let's imagine that for girls, the baseline rate of depression diagnosis is 10 (out of 100)--we'd then assume that the risk for girls who are insecure about their appearance would have a rate of about 18.4 (out of 100). For boys, the baseline rate of depression might also be 10 (out of 100); we'd calculate that the risk for boys who are insecure about their appearance would have a rate of depression diagnosis of about 28.5 (out of 100).

a) It takes three variables to have a moderator--two for a core bivariate relationship and one more variable as the moderator. Identify the three players in this example:

Core bivariate relationship (2 variables):

Moderator variable:

b) In this example, are the variables manipulated or measured?

c) We can depict a moderator two ways: with a table or with a figure. Let's do a table first--this will be similar to Table 8.5 and 8.6. Note that you don't have to use the numbers provided (285% or 84%)--just think about how strong the relationships are, relative to each other.

On each line, enter one level of the moderator variable | What is the core bivariate relationship and how strong is it? (strong, weak, or zero) |

d) We can also depict a moderator with a graph. Sketch a pair of bar or line graphs. Label one graph for boys and one for girls. On the x-axis, put the "body dissatisfaction" variable; put the other variable on the y-axis. If you are making line graphs, use *steepness* to depict the strengths of the two relationships (which graph will be steeper--boys or girls?). If you are making bar graphs, use the* difference between the bars* to depict the strength of the relationship (which will be stronger--boys or girls?).

e) Now write a sentence similar to those in Figure 9.14: "_________ moderates the relationship between _______ and _________, such that ___________."

**Refining your understanding:** A moderator is a *relationship changer: *it changes the *strength* or *direction* of some core bivariate relationship. In the present example, it's also true that there were gender differences in one of the variables--relative level of body dissatisfaction:

Well over half of teens, 61 percent, experience body dissatisfaction.... Nearly one in three girls and around one in seven boys were insecure about their weight, and around one quarter girls and one in seven boys were dissatisfied with their figure.

Sometimes students confuse simple differences (i.e., boys are lower than girls on body dissatisfaction) with moderators (i.e., boys with body dissatisfaction are more vulnerable to depression than girls are). Take a moment and study the difference. How many variables are involved in each statement:

boys are lower than girls on body dissatisfaction

boys with body dissatisfaction are more vulnerable to depression than girls with body dissatisfaction are

f) Challenge yourself to create a scatterplot in which body dissatisfaction is on one axis and risk of severe depression is on the other. Use one color of dot to represent boys; pick another for girls. Carefully place dots on this scatterplot to represent the two major findings--that boys are generally lower than girls on body dissatisfaction, AND that boys who do have body dissatisfaction are more at risk for severe depression. (Consult Figure 8.17 in the 4th edition for a model.)