Hello, I have to do a final project for my Statistics class. I chose to do a project on the relationship between a car's weight and its 4 crash test ratings (2 front for passenger and driver and 2 side for front and rear). The ratings are 1 - 5 (the number of stars); the higher the rating, the safer the car. I got all my data from crashtest.com. In all, I got data for 187 cars - that is, the weight and the 4 ratings. However, when I did a scatterplot of any 1 of the front ratings vs. weight the r coefficient was very close to 0 and the plot did not show a pattern. When I plotted the side ratings vs. weight, r was about .6 in both cases (a mild relationship). Thus, I can't really conclude anything from this. What I am thinking of doing and what I am asking about is this: If I separate my data into 9 groups based on weight where each group spans 500 pounds so that group1 has cars with weights 1501 - 2000 and group 9 has 5501 - 6000 and then take the mean of all 4 ratings in each of these groups and plot them against the mean weight in each group for all 4 ratings (again, 4 separate plots), will I get a more definite relationship (I haven't done it yet so I don't know) and even more importantly, will this apparent relationship be statistically significant and why or why not (why does grouping help or why not)? If not, can you suggest something else that I may be able to do. Thanks so much for your help.
Cheers, Serge . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
