Question

What information is considered an observation in statistics? For example, I have a set of data in which each column is labelled such as age, gender, etc. and there is data in each column. Which information is considered the "observation"?

Answer 1

An observation in statistics is a value of something of interest you’re measuring or counting during a study or experiment: a person’s height, a bank account value at a certain point in time, or number of animals. “Observation unit” means the same thing in this context. For example, let’s say you are measuring how well your savings perform over the period of one year. You record one measurement (your bank account balance) every three months for a total of four observations:

• March = $564
• June = $576
• September = $587
• December = $599

Note that an “observation” doesn’t imply that you observed it. Somebody else might have measured it. Or it could be data you found in a dusty file and have no idea where it came from. Lets say you found one thousand files. Each file could be an observation, or each page within the file; a lot depends on you, and how you choose to break apart your data. Basically, a lot depends on what you’re looking for. Let’s say your files contain data from an 1800’s asylum, and you’re interested in the health of women in the asylum. The file covers would be of no use to you, so they obviously would not be “observations”, but what about the rest of the contents? You might choose to take each person’s file and classify that as an experimental unit. However, if you’re only interested in the rate of, say, syphilis, then you might only take each syphilis case.

you have the data table containing information regarding height,age,weight of different individual,here every individual is an observation or every row is an observation.