Question

Leon James and Diane Nahl posted results of a survey in August of 2000, where respondents were asked about various driving habits. This table classifies 1086 participants according to type of car driven, and whether or not they were in the habit of making insulting gestures at other drivers. Notice that, unlike most tables encountered in this chapter, the explanatory variable (type of car) is indicated in columns, and the response (gestures or not) is in rows. Economy Family Luxury Sports Truck Utility Van Total | Gestures 796516 58 42 328 300 No Gestures 281 17045 95 77 79 39 786 Total 360 235 61 153 119 111 47 1086

Answer 1

(b)

For each type,

Conditional probability that surveyed drivers of that type of car makes insulting gestures is the ratio of number of cases of gesturing to total number of cars of that type.

So, conditional probabilities for each type of car are as follows.

(i)

Economy:

(ii)

Family:

(iii)

Luxury:

(iv)

Sports:

(v)

Truck:

(vi)

Utility:

(vii)

Van:

(h)

Number of cars of types economy, family, luxury or van

Total number of cars of different types

So, probability of driving an economy car, a family car, a luxury car or a van

(i)

Number of insulting gestures from an economy car, a family car, a luxury car or a van

So, probability of making insulting gestures, given that someone drives an economy car, a family car, a luxury car or a van