" aria-label="anchor" href="#metric-aggregation-per-epoch"></a>
</h2>
<p>Most metrics are at first calculated at the same resolution as the
raw data, which reflects a tiny fraction of a second. The exact number
of data points per second also known as the sampling rate can vary
between studies. With a different sampling rate values are not directly
comparable. However, by aggregating metric values per larger time
window, known as an epoch, we can make the values more comparable. So,
GGIR aggregates these val