Dr. Farah is an educational psychologist who is interested in studying the potential causal relationship between doing homework and academic achievement. In January, Dr. Farah has her students report their fall GPA (a measure of academic achievement) and estimate how many hours they spent doing homework during a typical week in the fall semester. In May, Dr. Farah measures the same variables again (the estimated number of hours spent doing homework during a typical week in the spring semester and their spring GPA). She finds the following correlations.
Imagine that Dr. Farah noted a cyclical, reinforcing relationship between homework and academic achievement. For this to be case, which of the following correlations would need to be significant?

Doogan corporation makes a product with the following standard costs: standard quantity or hours standard price or rate direct materials 2.0 grams $ 7.00 per gram direct labor 1.6 hours $ 12.00 per hour variable overhead 1.6 hours $ 6.00 per hour the company produced 5,000 units in january using 10,340 grams of direct material and 2,320 direct labor-hours. during the month, the company purchased 10,910 grams of the direct material at $7.30 per gram. the actual direct labor rate was $12.85 per hour and the actual variable overhead rate was $5.80 per hour. the company applies variable overhead on the basis of direct labor-hours. the direct materials purchases variance is computed when the materials are purchased. the materials quantity variance for january is: