How does Roblox Analytics interpolation work? Is it based off of real stats, or just visual?

Hi,

I was wondering why there is interpolation between data points for analytics values, such as Playtime or Retention, and why the interpolation is not linear?

More specifically I would like to know, is the interpolation based off of real data? Or is it just for style and if it is style, why not linear?

Here is an example:

-Red is linear interpolation
-Blue is roblox interpolation

Thanks