From my visit to the Grinnell farmers’ market on August 11, 2006, I designed both a template for interactions between vendors and customers, and a set of use cases depicting these interactions.

In all interactions between vendors and buyers, there are two constants: the customer walking over to the stand, and the customer leaving the stand. After these obvious aspects of the interaction, there are three variables in any vendor-customer interaction: amount of time spent speaking with the vendor, amount of time spent examining the goods on offer, and the amount of goods ultimately bought by the customer. A fourth variable would be the topics discussed by the vendor and customer (where the goods were grown/made, how much they cost, etc.); unfortunately, my position as an observer did not allow me to watch the interactions closely enough to observe interactions in such detail.

Given this template for buyer-seller interactions, all use case observations differ in only the extent to which each of the three variables is present (I designed the list of constants and variables in buyer-seller interactions following my use case observations, not prior to them. I noticed in my observations that all interactions differed in only these three areas, which induced me to create a list of possible variables). Interactions also differ in the characteristics of the customer and the goods sold at the particular stand.

Some of the more common interactions I observed included: (Though each of these interactions were observed more than once, a common gender/age (ages are my estimates) of the customer is included, along with a typical vendor station where the interaction was observed)

Note: Along with every use case description, I have attached a diagram, located at the end of this document. Description titles correspond with diagram titles (for example, Use Case Observation 1 is depicted graphically in the attached .GIF document with the same name).

Use Case Observation 1: 45 year old female customer glances at goods while passing by produce stand.

(On a scale of 1-10…)

Time spent speaking with vendor: 0
Time spent examining goods on offer: 0
Amount of goods bought: 0

Use Case Observation 2: 40 year old male customer talks extensively with vendor at produce stand, then buys a good.

Time spent speaking with vendor: 10
Time spent examining goods on offer: 10
Amount of goods bought: 5 (only one good was bought, but on a scale of 1-10 in the goings-on in the market, this falls in the middle).

Use Case Observation 3: 30 female customer asks question of vendor at crafts station, then leaves.

Time spent speaking with vendor: 2
Time spent examining goods on offer: 2
Amount of goods bought: 0

Use Case Observation 4: 20 female customer buys a good at kettle corn station, without asking any questions.

Time spent speaking with vendor: 0
Time spent examining goods on offer: 1
Amount of goods bought: 5

Use Case Observation 5: 60 female and 60 male customer speak with produce station vendor for a while, while examining goods, then buy a good.

Time spent speaking with vendor: 8
Time spent examining goods on offer: 10
Amount of goods bought: 5

Use Case Observation 6: 50 female customer examines goods at produce station, then buys something.

Time spent speaking with vendor: 0
Time spent examining goods on offer: 8
Amount of goods bought: 5

Use Case Observation 7: 40 female customer examines goods at baked goods station, then leaves.

Time spent speaking with vendor: 0
Time spent examining goods on offer: 5
Amount of goods bought: 0

Use Case Observation 8: 55 male customer speaks with vendor at produce station extensively, then leaves.

Time spent speaking with vendor: 10
Time spent examining goods on offer: 2
Amount of goods bought: 0

Use Case Observation 9: 20 male customer asks a question of vendor at produce station, then buys good.

Time spent speaking with vendor: 2
Time spent examining goods on offer: 2
Amount of goods bought: 5

Use Case Observation 10: 45 female customer asks several questions of vendor at produce station while examining goods, then buys a few different goods.

Time spent speaking with vendor: 8
Time spent examining goods on offer: 10
Amount of goods bought: 10