But I can judge whether I'm wasting money with google ads vs using TV ads or billboards. Do NPR promise me my sponsorship will result in increased sales or that

But I can judge whether I'm wasting money with google ads vs using TV ads or billboards. Do NPR promise me my sponsorship will result in increased sales or that it's the "lowest" possible price? Maybe some people hearing an NPR sponsorship would have bought from me anyways - is this now a crime?