Project Summary:
Purpose/ Hypothesis
The study performed was designed to determine if you are getting value for your money when
buying different egg sizes, and which size gives you the most egg for your money. Because eggs
are graded on a set minimum weight (determined by the Canadian government), it is
hypothesized that when buying eggs of smaller size classes (small, medium) consumers will get
higher value per dollar than when buying eggs in the larger size classes (large, extra-large). The
reasoning behind the hypothesis is that, if the weights of all eggs follow a normal distribution,
the distribution of weights within size classes should be skewed towards larger sizes in the
smaller classes and smaller sizes in the larger classes.
Design/Method
Individual eggs will be weighed with a Pesola scale (to 1 g) and these weights will be recorded.
The minimum, maximum and mean weight will be calculated for each size class and the
percentage of eggs falling outside the government guidelines will be calculated. The percentage
difference in the mean weight of a dozen eggs of different size classes will be calculated and
compared to the percentage difference in prices of the different size classes. This analysis will
determine if consumers are getting what they pay for, that is the percentage difference in mass
between classes should match the percentage difference in price between classes.
Observations
There was a clear difference in weight between eggs classified as small, medium, large, and
extra-large (see Table 1, Figure 1). However, within the different size classes, not all eggs met the
weight guidelines set by the Canadian government. For example all small class eggs exceeded
the set minimum but almost 10% were within the weight range of medium eggs. In contrast, none
of the extra-large eggs exceeded the weight limits and almost 5% were smaller than the set
minimum. The midpoint of the small size class is 45g but, as predicted, the mean of eggs
measured exceeded this midpoint. The same occurred among eggs in the medium and large size
classes. However the mean size of extra-large eggs was much lower (65.2 g) than the class
midpoint (66 g).
Interpretation/Conclusions/Applications
The data collected shows that there is an imperfect fit between the way eggs are classified at
supermarkets and the guidelines set by the Canadian government. 5% of the eggs that were
measured did not meet the guidelines. This may seem like a minor deviation from the rules but it
would, over the long term, amount to a substantial loss or gain of profit for supermarkets and
gain or loss of value for the consumer. I am in the process of collecting data on the prices of
eggs in supermarkets in Kingston to determine if consumers are getting what they pay for when
they buy eggs of a certain size.
Project No. 2223 Division: Physical and Math