The 2013 World Drug Report investigated the prevalence of drug use as a percentage of the population aged 15 to 64. Data from 32 European countries are shown in the following scatter plot and regression analysis. (Source: World Drug Report, 2013. www.unodc .org/unodc/en/data-and-analysisAVDR-2013.html)

Response variable is Cocaine
R-squared = 25.8%
s = 0.7076 with 32 - 2 = 30 degrees of freedom
Variable Coefficient SE (Coeff) t-Ratio P-Value
Intercept 0.296899 0.2627 1.13 0.2673
Canabis 0.123638 0.0382 3.23 0.0030
a) Explain in context what the regression says.
b) State the hypothesis about the slope (both numerical and in words) that describes how use of marijuana is associated with other drugs.
c) Assuming that the assumptions for inference are satisfied, perform the hypothesis test and state your conclusion in context.
d) Explain what R-squared means in context.
e) Do these results indicate that marijuana use leads to the use of harder drugs? Explain.