Sodium nitrate, a preservative that is used in some processed meats, such as bacon, jerky, and luncheon

Question:

Sodium nitrate, a preservative that is used in some processed meats, such as bacon, jerky, and luncheon meats, could increase your heart disease risk. A consumer protection organization is evaluating the level of sodium nitrate (NaNO2) from sausages obtained from the three largest food processors€”P1, P2, and P3€”in the United States. Each manufacturer produces three grades of quality for their sausage€”Q1, Q2, and Q3. The processing of different grades of sausage from a common production run may involve different sources of raw materials and processing environments, and these factors sometimes are problematic. Each food processor submits two sausages of each grade from each of three production runs. The amount of NaNO2 is determined and is reported in the following table. The three food processors are the only processors under evaluation, the production runs were randomly selected and are representative of general production runs of each food processor.

a. What type of randomization was utilized in this experiment (completely randomized design, randomized complete block design, Latin square design, etc.)?
b. What type of treatment structure was used (single factor, crossed factors, nested factors, etc.)?
c. Identify each of the factors as being fixed or random.
d. Describe the experimental units for each factor and the measurement units.
e. Write a statistical model for this experiment, and include all necessary conditions on the model parameters and variables.