An advertisement for the online Pricing Psychology Report mentions the well-known phenomenon whereby people are much likelier to buy a product if it is priced at $9.99 rather than $10.00. It also recommends a way for online marketers to compare orders for merchandise advertised at two different prices, called "perfect A/B split price testing":5
a. The first visitor to your site sees price "A"
b. The second visitor sees price "B"
c. The third visitor sees price "A"
d. The fourth visitor sees price "B" etc. Is this method characterized as cluster sampling, haphazard sampling, systematic sampling, stratified sampling, or random sampling?