What is a back door?

Using least squares fitting, you are to fit the data sets to the following models and solve for the parameters ai , where i is the index of the parameter. the input/output data for the systems are linked in the bblearn site. for each of the systems use matlab to plot the supplied data vs. the model fit on one plot. include your code in the solutions. (a) linear fit "lineardata. mat" y=a1x^3 + a2x^2 + a3x + a4 (b) plant fit "plantdata. mat g(s) = a1/(s + a2)

Awell-diversified portfolio needs about 20-25 stocks from different categories is this true or false?

1. technician a says horsepower information can be used by consumers to compare the power of different automobile engines. technician b says that manufacturers will often list the horsepower output of their engines in the online service information. who is right?