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urban-meal-delivery-demand-.../tex/4_stu/5_training.tex
2020-10-04 23:58:46 +02:00

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\subsection{Impact of the Training Horizon}
\label{training}
Whereas it is reasonable to assume that forecasts become more accurate as the
training horizon expands, our study reveals some interesting findings.
First, without demand, \textit{trivial} indeed performs better with more
training material, but improved pattern recognition cannot be the cause
here.
Instead, we argue that the reason for this is that the longer there has been
no steady demand, the higher the chance that this will not change soon.
Further, if we focus on shorter training horizons, the sample will necessarily
contain cases where a pixel is initiated after a popular-to-be restaurant
joined the platform:
Demand grows fast making \textit{trivial} less accurate, and the pixel moves
to another cluster soon.
Second, with low demand, the best-performing \textit{hsma} becomes less
accurate with more training material.
While one could argue that this is due to \textit{hsma} not fitting a trend,
the less accurate \textit{hses} and \textit{hets} do fit a trend.
Instead, we argue that any low-demand time series naturally exhibits a high
noise-to-signal ratio, and \textit{hsma} is the least susceptible to
noise.
Then, to counter the missing trend term, the training horizon must be shorter.
With medium demand, a similar argument can be made; however, the
signal already becomes more apparent favoring \textit{hets} with more
training data.
Lastly, with high demand, the signal becomes so clear that more sophisticated
models can exploit longer training horizons.