Most users are not just interested in what the statistics look like for a topic right now; they want to compare them with data from the past. Well, there are many variables one must consider when comparing data over time. Some of these differences include:
For example, when comparing data from one Economic Census to the next, there are a couple of differences that stand out:
In order to understand random sampling, you need to become familiar with a couple of basic statistical concepts.
These two concepts work together to determine how accurate your survey results are. For example, if you have 90% confidence with an error of 4%, you are saying that if you were to conduct the same survey 100 times and calculated 90-percent confidence intervals each time, approximately 90 of the 100 intervals would contain the value of the population parameter.
If you are not sure what sort of error you can tolerate and what level of confidence you need, a good rule of thumb is to aim for 95% confidence with a 5% error level.
“Error” is also referred to as the "margin of error" and “Confidence” is also known as the "Confidence Level." In order to avoid confusion, these concepts will simply be referred to as "Error" and "Confidence".