Observations and data points

[Pia Donner]

Hello,
I'm often reading that people report the number of observations and data points. I know where to find the observations but I'm wondering what indicates my data points?
Thanks in advance!

[Maxence Morlet]

Synonyms; they both refer to the identical thing i.e. one observation, or in a dataset some refer to observations as rows

[Carlo Lazzaro]

Pia:
see https://dataconomy.com/2022/07/data-points/

[Nick Cox]

I see the phrase data points as arising from problems in which scatter plots are natural tools. So, in a talk someone might show a plot with data for two variables and if it's not obvious a natural question would be "How many data points do you have there?". (The undertones can very from hinting that you don't have enough data to be serious through neutral to envy that someone has an attractively large dataset,)

There is no real difficulty in extending that term to other spaces. Even if the data are all categorical, they exist in a space that is some union of the individual outcome spaces.

Beyond that, there are in my experience two nuances that may arise.

If there are missing values, it might be that the number of data points is regarded as the number of observations with non-missing data you have.

I would more commonly expect to read and even to write number of observations (cases, records) -- rather than number of data points -- in a more or less formal report (submission for a course, dissertation, thesis, journal paper, book). But number of data points is, in my view, fair terminology for graphics whenever the data are explicitly or implicitly based on, as said, data points. .