Sutton M.

asked • 06/09/20

What tells you that the relation is best fit by a linear model? Use principles about what kinds of functions have consistency in which types of rates of change?

Suppose a set of data about the spread (in hundreds of acres) of a food-borne bacteria (after t weeks) in lettuce has the following percentage rates of change: 0.9%, 1.3%, 1.1%, 1.0%, 1.3%, 1.0%; and the following average rates of change: 2.9, 2.4, 3.7, 3.1, 3.6, 3.2. Based only on the information given, and without doing any calculations, what type of model would you use? Why? (NOTE THAT the information given is not the actual data set. I have calculated the two types of rate of change for you. You should NOT BE CALCULATING ANYTHING!) 

Jeremiah T.

Here's a Statistics perspective: I look over the data and make a picture, either a scatterplot or a histogram. If the rates of change do not show any outliers and they stay about the same, as the lettuce data does, I try a linear model or linear regression. Does that make sense? Your data is nearly straight, which is needed for linear regression, but if it's not, we can find ways to make it more straight. So I'd use a linear model, remembering that a straight line can be written y = mx + b. m is the slope, and you can find the slope if you know the correlation, the standard deviation, and the mean.
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06/10/20

Stanton D.

Nope, I disagree. Just eyeballing the percentage rates of change values vs. t, one can see that they have essentially a zero slope. So the change is better modeled as constant percentages, i.e. it is an exponential growth. The average rates of change data trend upwards, so it is NOT a linear growth. -- How about that lettuce!! Better off growing your own, considering everything .... -- Cheers, -- Mr. d.
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06/28/20

Stanton D.

Nope, I disagree. Just eyeballing the percentage rates of change values vs. t, one can see that they have essentially a zero slope. So the change is better modeled as constant percentages, i.e. it is an exponential growth. The average rates of change data trend upwards, so it is NOT a linear growth. -- How about that lettuce!! Better off growing your own, considering everything .... -- Cheers, -- Mr. d.
Report

06/28/20

1 Expert Answer

By:

Omar L. answered • 09/05/20

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