How many ways is variance partitioned in a two-way ANOVA?

The greatest disadvantage of correlational research is that:

a) it has a limited range of values, being only –1 to +1. b) it does not support cause-and-effect conclusions. c) its value can be negative. d) its value can be zero.

Julie finds that the number of hours she sleeps each night is related to the scores she receives on quizzes the next day

As her sleep approaches 8 hours, her quiz scores improve; as her sleep drops to 5 hours, her quiz scores show a similar decline. Julie realizes that ______________________. a) there is a negative correlation between the number of hours she sleeps and her quiz grades b) there is a positive correlation between the number of hours she sleeps and her quiz grades c) her low quiz scores are caused by sleep deprivation the night before a quiz d) she should sleep about 10 hours a night to ensure 100 percent quiz grades