The midterm projects were impressive in diversity and quality.
Here are some of the most common faults, which can be avoided in the final project.
Bullet points. These are appropriate in presentations, but are best avoided in reports. Why?
Code. Generally, code should be copied into a report only when the specifics of coding are a topic of discussion. My notes are not the best role model for a report: I include plenty of code, in order to help discussion of the process of generating the analysis.
Fitted values. The so-called fitted values for ARMA models are the one-step forecasts.
These can look like a good match for the data even when the model has no predictive power beyond simply estimating the next data point using the current data point.
Usually, it is not interesting to note that a simple forecast (using the previous data point or the previous year at the same time) looks visually like a good match for the data.
It may be more interesting to note whether the fitted model does substantially better than a trivial forecast.
Taking logs. Remember to consider the possibility of transforming the data, usually a square root or log transform for non-negative data.
Complex conjugate ARMA roots. Several people noticed that roots had the form \(a\pm bi\), which is not statistically interesting since it is just the form of complex roots of a quadratic.