Here are week four and final observations on my supermarket experiment. The rules are laid out here and the  links to results from week 1, 2 and 3.

Week 4 results did not prove to be too different than week three results. The biggest changes were that tissue and snack bars in the ideal locations went on sale. The sale did not change the tissue results but made the snack bars in the ideal location cheaper than the non-ideal location for the first time ever. As per my rules, the % difference in such a case is 0%.

The results are below. I have also added the average % difference over the course of the experiment as a summary.

Baked Beans (398 ml can)

Ideal location- $1.19 (Heinz)
Less ideal location- $0.79 (Compliments)
Difference- $0.30
% Difference- 21

Average % difference over 4 weeks: 23.25%

As my week 1 post and a reader pointed out, I could not find another name brand in baked beans in my supermarket. This has obviously thrown the results off somewhat.

Olive Oil (1 Litre bottle)

Ideal location- $10.79 (Bertolii)
Less ideal location- $7.99 (Carapelli)
Difference- $2.80
% Difference- 26 *

Average % difference over 4 weeks: 28.25%

Snack Bars (175g box)

Ideal location-$2.49 (Kellogg’s Nutri Grain)- this item went on sale
Less ideal location- $2.99 (Quaker Chewy Bar)
Difference- $.50 in favor of the ideal location
% Difference-0 (as per my rules)

Average % difference over 4 weeks: 4.5%

As discussed above, it took a sale in order to get this item below the non-ideal location price.

Shampoo

Ideal location- $2.19 (Finesse, 330 ml)
Less ideal location- $1.99 (European Formula, 350 ml)
Difference- $0.20
% Difference-9

Average % difference over 4 weeks: 9

Shampoo never changed its price structure over these 4 weeks.

Tissue

Ideal location- $1.99 (120 sheets of 2 ply tissue by Kleenex)
Less ideal location- $1.29 (140 sheets of 2 ply tissue by Royale Ultra)
Difference- $0.70
% Difference-35

Average % difference over 4 weeks: 37.5

The ideal and non-ideal location went from 3 ply to 2 ply tissue this week; I suppose people do not need thick tissues in the summer time. As I have stated before, the % difference between these two items is actually greater due to the quantity difference. Kleenex charges more for less tissues in a box.

Based on a limited 4 week experiment, I can conclude the following:

1. Not accounting for taste, generally, you can save more money buying items from less ideal locations in a supermarket.
2. It took a sale in order to get any item in the ideal location to be priced less than the non-ideal location suggesting that it takes some price movement to occur before an exception to conclusion #1 arises.
3. Price difference in a discretionary item such as snack bars tend to be less than in staples. However, the comparison between olive oil is inconclusive given that there was no ideal or non-ideal location for this product in my supermarket and I could not find 2 brand name baked beans in my supermarket. Thus, this conclusion has a huge disclaimer on it.
4. Tissue had an abnormally high price difference relative to the other products. I have no concrete theories for this other than, based on pure conjuncture, Kleenex has such a dominant strangle-hold on this product that it can charge whatever it pleases and still make sales.
5. Shampoo, which is generally an item you would buy at a drug store rather than a supermarket (at least I do), tends to display very little price differential based on a limited sample size. It may be interesting to see how pricing operates in these types of bodily care items in a drug store where these types of items are bigger pulls for customers into a drug store than a supermarket (experiment part 2?).

That’s it for this experiment. Thanks for reading about it. There may be some sporadic posting for the next two weeks due to business travel. I may post twice in one day and then no posts the next day. Bear with me. Thanks.