Aregression model is used to forecast sales based on advertising dollars spent. the regression line is y=500+35x and the coefficient of determination is .90. which is the best statement about this forecasting model? a. for every $35 spent on advertising, sales increase by $1.
b. even if no money is spent on advertising, the company realizes $35 of sales.
c. the correlation between sales and advertising is positive.
d. the coefficient of correlation between sales and advertising is 0.81.

Agroup of student volunteers participates in a study designed to assess several behavioral interventions for improving output in a repetitive task. prior to the beginning of the study, all volunteers unknowingly observed, and their output is measured. at the beginning of the study, prior to any intervention, the volunteers perform the same task under the observation of a study administrator, and their overall output increases. which of the following terms describes this phenomenon? a. simpson's paradox b. hawthorne effect are d. novelty effect d. pygmalion effect e. observer-expectancy effect