Calculate the total cost and expected cost (per email) based on the confusion matrix you obtained in question. Assume the cost for each mis-classified email from Spam to Non-spam is 5, and from Non-spam to Spam is 100. [Hint: be careful with the dimensions of the confusion matrix: which are the "actuals" and which are the "predictions"?]

Aprice ceiling is “binding” if the price ceiling is set below the equilibrium price. suppose that the equilibrium price is $5. if a price ceiling is set at $6, this will not affect the market in any way since $5 remains a legally allowable price (since $5 < $6). a price ceiling of $6 is called a “non-binding” price ceiling. on the other hand, if the price ceiling is set at $4, the price ceiling is “binding” because the natural equilibrium price is $5 but that is no longer allowed. what happens when there is a binding price ceiling? at a price below the equilibrium price, quantity demanded exceeds quantity supplied. there is a shortage. normally, price increases eliminate shortages by increasing quantity supplied and decreasing quantity demanded. in this case, however, price increases are not allowed past the price ceiling. we therefore predict that the observed market price will be right at the price ceiling and there will be a permanent shortage. the observed quantity bought and sold will be dictated by the quantity supplied at the price ceiling. although consumers would like to buy more, there are no more units for sale

Consider how health insurance affects the quantity of health care services performed. suppose that the typical medical procedure has a cost of $160, yet a person with health insurance pays only $40 out of pocket. her insurance company pays the remaining $120. (the insurance company recoups the $120 through premiums, but the premium a person pays does not depend on how many procedures that person chooses to undergo.) consider the following demand curve in the market for medical care. use the black point (plus symbol) to indicate the quantity of procedures demanded if each procedure has a price of $160. then use the grey point (star symbol) to indicate the quantity of procedures demanded if each procedure has a price of $40. q d at p=$160 q d at p=$40 0 10 20 30 40 50 60 70 80 90 100 200 180 160 140 120 100 80 60 40 20 0 price of medical procedures quantity of medical procedures demand if the cost of each procedure to society is truly $160, the quantity that maximizes total surplus is procedures. economists often blame the health insurance system for excessive use of medical care. given your analysis, the use of care might be viewed as excessive because consumers get procedures whose value is than the cost of producing them.

At cooly cola, we are testing the appeal of our new diet one cola. in a taste test of 250 randomly chosen cola drinkers, 200 consumers preferred diet one cola to the leading brand. assuming that the sample were large enough, the large-sample 95% confidence interval for the population proportion of cola drinkers that prefer diet one cola would be: