On the prevalence of bumperstickers in South Jersey
This research seeks to determine the actual prevalence of bumperstickers. Bumperstickers are thought
of as a common form of personal expression in American society, but they have not been studied
systematically.
Three hypotheses were tested. The first hypothesis was that bumperstickers adorn about 33% of the
cars on the road. This proportion was based on the experimenter's estimate that about 1 of every 3
cars seen in driving had a sticker. The most popular sticker was hypothesized to be stickers about
football teams. This was because the observations were made in the fall in a relatively quiet
election campaign, and because of the experimenter's belief that sports fans were more likely to
purchase bumper stickers. Finally, it was hypothesized that a dependency would be observed in the
number of stickers on a vehicle. That is, it was likely that if a person had put one sticker on a
car, the person would be more likely to put on additional stickers.
Method
Definition. For the purposes of this research, a bumper sticker was defined as a sticker placed on
the bumper or back of any non-commercial vehicle. Certain stickers were excluded, namely parking
decals, AAA decals, and country-of-origin decals.
Procedure. One lane of the Cherry Hill Mall parking lot was chosen for the data collection site.
Sampling was carried out on a Saturday afternoon, from 1:30 to 2:5 pm; a weekend afternoon was
selected in order to obtain a good variety of vehicles. Sampling was done in a lot next to the west
entrance to the J.C. Penney's department store. Starting with the first row on the left from the
entrance, observations were recorded for every car in each row (there were 4 rows in total), until
200 observations were made.
The number of bumperstickers for each vehicle was recorded, and stickers were classified into the
categories of travel, newspaper, radio stations, and miscellaneous. Travel stickers were any
stickers that named vacation resort areas and camping sites, such as "Disney World" or "New Jersey
and You - Perfect together". Newspaper stickers were any stickers that carried promotions for a
Newspaper, such as "I love the Courier-Post". Radio station stickers were any stickers that promoted
a designated radio station, such as WYSP. Miscellaneous stickers were any stickers that did not fit
into the preceding 3 groups.
Results
The proportion of vehicles in the sample of 200 with bumper stickers was .10. This was significantly
fewer than initially hypothesized, z = 6.97, p < .01. The most common stickers were those that
identified a radio station (20%). To examine the hypothesis of dependence, I compared the observed
distribution showing the number of bumper stickers per car with the corresponding distribution
predicted from a geometric progression. The geometric progression is a simple model of independence.
Table 1 summarizes this analysis. The table shows the number of cars observed with 0, 1, 2, 3 or 4
bumperstickers and also the number predicted by a geometric progression, using the observed
proportion of cars with at least one sticker, namely, .10.
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Insert Table 1 about here
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A chi-square test was used to compare the observed and predicted distributions, and the result of
this test indicated that there was no evidence of dependence, c 2(4) = 5.43, p > .05.
Discussion
This research found that bumperstickers were considerably less prevalent than initially
hypothesized. A likely source of error is the experimenter's misperception of how prevalent
bumperstickers actually are. It is also possible that the sample of cars did not
provide a representative estimate of cars in South Jersey, although it was assumed that most
residents in the suburbs at least are likely to shop at one or more of the large shopping malls in
the area.