Followup: Dalgona 2ᵏ Showdown, Espresso vs. Coffee

Our recent look at preparation times for Dalgona coffee produced data that lent itself to 2 analysis.  However, a closer look at the collected data indicated that with a single extra trial we could compare the variation explained by instant coffee type and beater type.

Procedure:

  1. Perform an experiment that produces most of the required data.
  2. Time Dalgona preparation with instant espresso and silicone beaters in a small bowl.
  3. Repeat analysis with instant coffee type and beater type as factors.

Data:

The additional trial with instant espresso using silicone coated beaters in a small bowl took 94 seconds.  This sample, combined with the previously collected data, is shown in the table below.  All times are in seconds.

Beater Type (B)
Coffee Type (A) Bare Metal Silicone Coated
Coffee 63 90
Espresso 45 94

Analysis:

The data, when put into the sign table for a two factor experiment, is shown below.

I A B AB y
1 -1 -1 1 63
1 1 -1 -1 45
1 -1 1 -1 90
1 1 1 1 94
292 -14 76 22 Total
73.00 -3.50 19.00 5.50 Total/2

The resulting SST is 1614, and the percent of variation explained by the each factor is 3.04%, 89.47%, and 7.50% for factors A (coffee type), B (beater type), and AB (the interaction between A and B) respectively.  Thus the beater type explains most of the variation in preparation time, but coffee type, in some way, does contribute quite a bit.  Unfortunately we do not have enough data to determine if the variation explained by the coffee type is statistically significant.

Conclusion:

By reusing data collected in a previous experiment and adding one additional sample, the relative variation of beater type and instant coffee type was examined.  The beater type alone accounted for approximately 90% of the variation, with an additional 7.5% explained by the interaction between type of coffee and the beater type.

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