Читать книгу Introduction to Abnormal Child and Adolescent Psychology - Robert Weis - Страница 127

Surveys can also be used to predict children’s behavior or developmental outcomes. Some researchers are interested in identifying possible risk factors for ADHD. For example, the genes that children inherit from their parents, complications during pregnancy or delivery, and exposure to illnesses or toxins in early childhood can increase the likelihood that children will develop the disorder. Other researchers focus on protective factors that might lower a child’s likelihood of developing symptoms. For example, mothers who receive prenatal medical care, who avoid alcohol and other drugs during pregnancy, and who manage stress after delivery may lower their child’s risk for ADHD. Still other researchers explore children’s prognosis or developmental outcomes. For example, some children with ADHD may develop academic problems, depression, or substance use disorders later in life. Correlational studies allow researchers to explore possible relationships between variables like these (Kazdin, 2017).

Researchers usually quantify the magnitude of the association between two variables using a correlation coefficient. The Pearson product–moment correlation coefficient (r) is the most commonly used statistic. It reflects the linear relationship between two variables. Correlation coefficients range from 1.0 to –1.0.

The strength of association is determined by the absolute value of the number. Coefficients near 1.0 or –1.0 indicate strong covariation; if we know the value of one variable, we can predict the other with accuracy. Coefficients near 0 indicate weak or absent covariation; the value of one variable does not tell us much about the value of the other.

The direction of the association is determined by the sign of the coefficient. Positive values indicate a direct association between variables; as one variable increases, the other increases. Negative values indicate an inverse association; as one variable increases, the other decreases.

Humphreys and colleagues (2013) used correlation coefficients to investigate the association between children’s ADHD symptoms and their social functioning. They asked parents to rate the severity of their children’s ADHD symptoms, the degree of stress that they experienced caring for their children at home, and the quality of their children’s relationships with peers. The researchers found a positive correlation (r = .32) between children’s ADHD symptoms and parenting stress at home: the greater children’s symptoms, the higher their parents’ stress. In contrast, the researchers found a negative correlation (r = –.31) between children’s ADHD symptoms and the quality of their peer interactions: the greater children’s symptoms, the fewer friends they had at school.