# the true parameter of confidence interval in a real life example

A margin of error and a confidence interval are pretty much the same thing - it's the interval in which you are quite confident that the true parameter lies. If you have a 95% confidence interval, that means that if you were to repeat your experiment, 95% of the time the true parameter value would fall within your interval. Roughly speaking, there's a 95% chance that the interval contains the true value. The margin of error is simply describing the width of your confidence interval. So, if you have a confidence interval of [4, 6], you can say that your parameter estimate is 5 with a margin of error of 1.

where the term "true parameter" is used.

I am trying to understand that term. I searched a bit and got a post What, precisely, is a confidence interval?, which seems to talk about CI theoretically without a real life example, which is hard for me to understand.

Assume the U.S. Census Bureau published a survey of people in poverty in 1995. The survey stated a confidence level of 90% for the statistics “The number of people in poverty in the United States is 35,534,124 to 37,315,094.”

What the "true parameter" is in the example of Census Bureau's survey? Could someone please give a hint?

The example is adapted from source

• Another of the many "confidence interval" meaning questions worth reading is stats.stackexchange.com/questions/26450/… – Henry Apr 7 '20 at 14:16
• @Henry Thank you. 230 upvotes indicates that post is really worth reading. I will read it thoroughly and carefully when I get a clear understanding of the basic concept with some real life examples. Would you please recommend some discussion about CI with real life examples, e.g. poll, survey, screening some kind of disease? – WXJ96163 Apr 7 '20 at 14:26
• @WXJ96163 it's an interesting request, but you seem to have enough top down exposure to statistics, what's seems to be lacking for you is a theoretical basis. I'm not sure if it's considered off-topic. – AdamO Apr 7 '20 at 15:17
• This question appears to answer itself, because the phrase in the quotation "The number of people in poverty in the United States" describes the "true parameter." – whuber Mar 18 at 13:30