You work for a construction firm who need to be able to accurately predict the compressive strength of concrete given variables including the concrete composition and its age. You are aware that the relationship between these different components and the concrete strength is complex, however you have been asked to investigate how well a simple linear regression model works for prediction. Using the provided data given in the link below (Concrete_Data.xls), develop models to predict:

1. Concrete strength from the single best indicator variable;

2. Concrete strength from all variables.

With the second model, determine if any variables are not contributing significantly to the model, and what impact removing these has on prediction performance. Comment on the final model and its accuracy. You should draw on the unit content concerning correlation and regression to answer this question (Provide a MATLAB code and visualisations to justify your response.)

LINK TO FILE: https://www.dropbox.com/s/65vsy4gkm4uy6ab/Concrete_Data.xls?dl=0