In preparation for my end of semester R exam, I've been working on the following CSV file which was modelled on R, which I'm currently having problems figuring out. The excercise is from the textbook'Applied Statistics: Principles and Examples' by D. David Roxbee Cox.
The data is taken from a real study into Light Water Reactor (LWR) power plants constructed in the USA in the 1970s. The aim of the study was to develop a model that could be used to model the capital cost involved in the construction of LWR power plants. The data set includes 32 LWR power plants and contains the following variables:
The titles PR, NE, CT, BW and PT have outputs that consist of 1 and 0 where 1=Yes and 0=No.
The data set includes 32 LWR power plants and contains the following variables:
Now that I have introduced the domain of the question - here is my problem:
I've been asked to 'add suitable terms' to that model in order to investigate whether there is good reason to believe that the impact of a power plant's capacity on construction costs might not be the same for plants that did have a LWR on the same site previously and those that did not.
The summary results of my final model in R is shown below:
Therefore, the equation of my final model is:
C = -541.82231+ 26.11545T1+ 5.22321T2+ 0.41890S- 94.33786PR+108.34622NE- 132.58098PT
I tried fitting a model assessing just the S (power capacity) and PR (whether LWR existed on the same site previously) terms against C (construction cost) but the wording of the question states 'add suitable terms' to that model in order to investigate...' causes me to believe what I wanted to do is wrong because I would have been taking out terms.
Does anyone know what suitable terms I should add and how I test the correlation?
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