Industrial Statistics with Minitab

25.2 Power Plant

The file POWER_PLANT.MTW contains data corresponding to 50 days of operation of a thermal power station. Each row corresponds to daily data and the columns are:

Col.	Name	Content
C1	Yield	Yield of the thermal power plant
C2	Power	Average power
C3	Fuel	Combustible used (0: Fuel, 1: Gas)
C4	FF	Form factor of the power curve. Measures the variation of the power throughout the day.
C5	Steam Temp.	Live steam temperature
C6	Air Temp.	Air temperature (environment)
C7	Seawater Temp.	Seawater temperature (cold source)
C8	Day	Weekday (1: Monday, 2: Tuesday, …)

The aim consists in building a model that explains the plant's yield as a function of the variables available.

First, it should be clear that the variable Day, as such (qualitative variable with more than two categories), cannot be a candidate to be included in the model. However, what can be done is to encode it as 0=working day (Monday to Friday) and 1=weekend (Saturday and Sunday). This distinction seems reasonable to the technicians, because on weekends there is less demand and that could affect the performance of the power plant.

Data > Code > Numeric to a Numeric

With the new variable created, we carry out an exploratory analysis of the data.

Graph > Matrix Plot: Simple

As there ...