Results from surveys are usually quoted along with a with a value called confidence interval

A sample in a statistical study refers to the complete number of the set of people or things being studied

Stating goals of a statistical study precisely means  to determine the population to be studied and stating want you what to learn about it.

In a statistical study a census is a collection of data from a representative sample 

What is the name of the scale by which tornado strength is expressed?

Which variable gas enters the atmosphere via digestion and decomposition processes?

When feasible the larger sample sizes are more preferable for statistical studies.

Results from surveys are usually quoted along with a with a value called confidence level

At which point do clouds produce rain?

A population is a subset of the sample from which data are actually obtained.