This Fox News article describes the results of an empirical journal article (published in Child Development), presenting the results for a popular audience.  Here is an excerpt from the journalist's description:

The researchers assessed the infants' temperaments and the mothers' parenting styles in the first six months of life (by observing the pair during feeding time) and during the toddler years… The researchers followed up with the mothers and the children's teachers when their kids were in kindergarten (ages 5 and 6).

The results showed that

…children who exhibit aggressive, defiant and explosive behavior by the time they're in kindergarten very often have tumultuous relationships with their parents from early on.

What they didn't find was a correlation between difficult early-life behaviors of the child (if the child was irritable or quick to switch mood in his or her first six months) and later aggressive actions and attitudes.

a.) Is this study correlational or experimental?  How do you know?

b.) There are four variables described in the exerpt above.  What are they?

c.) Following the model in Figure 8.3, sketch the results of this study.  The exact correlations are not given here, but you can estimate which correlation is strongest. 

d.) The headline of the story is "Negative parenting starts aggressive personalities early."  How does the study establish temporal precedence for this causal claim?  Can the study establish internal validity? If so, how?

There's more to the study than revealed here–read the full journalist's coverage or look for the original study in the journal Child Development in your library.