🌐
MathBlog
mathblog.com › statistics › definitions › z-score › ci › 99-to-z
99% Confidence Interval to Z-score
April 22, 2024 - Calculate the Proportion of Your Area Within the Interval: Proportion (P) = (A – 0.9949) / ΔA = (0.9950 – 0.9949) / 0.0002 = 0.5 ... For most general purposes, educational contexts, and preliminary analyses, using an approximation like ...
🌐
Alchemer
alchemer.com › home › blog › how to calculate confidence intervals
Mastering the Calculation of Confidence Intervals
December 5, 2024 - Since they have decided to use a 95 percent confidence interval, the researchers determine that Z = 1.960. Next, the researchers would need to plug their known values into the formula.
Discussions

Explanation of confidence interval in layman terms
Your class interpretation is practical but technically wrong. Your initial thought is correct. We cannot draw probabilistic conclusions about the true value because it is fixed and unknown. We draw conclusions about the interval and we then extrapolate from that. Statistically all we say is that over repetitions of producing a 99% confidence intervals, 99% of them will include the true value. Now we lose our ability to speak about probabilities but we can still draw some logical conclusions. I have one 99% CI. It’s rather unlikely that I happened to pull the 1/100 that doesn’t include the population parameter. Therefore, this interval is a good viable range for the population parameter More on reddit.com
🌐 r/AskStatistics
2
3
November 7, 2023
[Q] If I want to compute the 99% confidence interval for the slope in linear regression analysis in R, does confint(lm(Y~X), level = 0.99) give me the right answer?
Which standard error are you using? More on reddit.com
🌐 r/statistics
13
2
February 21, 2021
Need help calculating the 99% confidence level (I think?) for an event.
Here’s my answer; feel free to correct if wrong. I’d recommend evaluating using Excel or your favorite programming language to solve for n. More on reddit.com
🌐 r/askmath
2
4
December 9, 2022
Finding a 99% Wald Confidence Interval
The literal default will produce Wald CIs: confint.default(health.logit, level=.99) However, the command you are using — i.e., confint() — will produce the profile likelihood CI. You can run both and see if there is a difference, but generally they will be very similar. If there is a difference, it is likely driven by a small sample size and PL is superior. (PL is generally superior in most cases but the difference becomes less meaningful in larger samples.) I can't cite documentation that PL is being used here, but you can just run this model in another stats package where you can verify the method (e.g., SAS or Stata). Edit: Formatting. More on reddit.com
🌐 r/rstats
1
1
February 10, 2014
People also ask

What is the Z-score for a 99% confidence interval?

The z-score for a two-sided 99% confidence interval is 2.807, which is the 99.5-th quantile of the standard normal distribution N(0,1).

🌐
omnicalculator.com
omnicalculator.com › statistics › 99-confidence-interval
99% Confidence Interval Calculator
Why use a 99% confidence interval instead of 95%?
The 99% level gives you more confidence your range includes the true value but at the cost of a wider interval. It’s handy when you want to be extra cautious, like in medical studies or critical quality control.
🌐
smart.dhgate.com
smart.dhgate.com › home › a step-by-step guide to calculating a 99% confidence interval with practical examples
A Step-by-Step Guide to Calculating a 99% Confidence Interval with ...
How to find the margin of error for a 99% confidence interval?

To find the margin of error for a 99% confidence interval:

  1. Find Z(0.99) (the z-score for 99% confidence) in the statistical table.
    Z(0.99) = 2.576
  2. Calculate the standard error with the formula SE = σ/√n, where σ is the standard deviation and n is the sample size.
  3. Multiply Z(0.99) by the standard error to obtain the margin of error, ME.
    ME = Z(0.99) × SE
🌐
omnicalculator.com
omnicalculator.com › statistics › 99-confidence-interval
99% Confidence Interval Calculator
🌐
Dhgate
smart.dhgate.com › home › a step-by-step guide to calculating a 99% confidence interval with practical examples
A Step-by-Step Guide to Calculating a 99% Confidence Interval with Practical Examples - Smart.DHgate – Trusted Buying Guides for Global Shoppers
November 9, 2025 - Imagine you’re trying to estimate some unknown number about a big group—like the average amount of sleep people in your city really get each night. You can’t
🌐
AnalystPrep
analystprep.com › home › confidence intervals
Confidence Intervals Explained | CFA Level 1
December 2, 2024 - Therefore, our confidence interval for μ is (123.36, 129.84). Use the data from the example above to calculate a two-tailed 99% confidence interval for the population mean.
🌐
Omni Calculator
omnicalculator.com › statistics › 99-confidence-interval
99% Confidence Interval Calculator
June 11, 2024 - Z(0.99)Z(0.99) — the z-score corresponding to the chosen confidence level (which you'll find in statistical tables). Add and subtract the margin of error value from the mean to obtain your confidence interval.
🌐
Indeed
indeed.com › career-advice › career-development › how-to-calculate-confidence-interval
How To Calculate the Confidence Interval (With Examples) | Indeed.com
3 days ago - Using the test score example, calculate the confidence interval assuming you have a confidence level or Z-value of 95%:Confidence interval = 85.5 ± 0.95(45.25 ÷ √10) = 85.5 ± 0.95(45.25 ÷ 3.16) = 85.5 ± 0.95(14.32) = 85.5 ± 13.6 = 99.1, ...
🌐
Simply Psychology
simplypsychology.org › statistics › confidence intervals explained: examples, formula & interpretation
Confidence Intervals in Statistics: Examples & Interpretation
October 11, 2023 - So, the confidence interval is (85 – (1.96*(5/sqrt(30))), 85 + (1.96*(5/sqrt(30))) = (83.21, 86.79). For a 99% confidence interval and a sample size > 30, we typically use a z-score of 2.58.
Find elsewhere
🌐
New York State Department of Health
health.ny.gov › diseases › chronic › confint.htm
Confidence Intervals - Statistics Teaching Tools - New York State Department of Health
With a 90 percent confidence interval, you have a 10 percent chance of being wrong. A 99 percent confidence interval would be wider than a 95 percent confidence interval (for example, plus or minus 4.5 percent instead of 3.5 percent).
🌐
Statistics LibreTexts
stats.libretexts.org › campus bookshelves › saint mary's college, notre dame › bfe 1201 statistical methods for finance (kuter) › 6: interval estimates
6.2: A Confidence Interval for a Population Mean- Standard Deviation Known or Large Sample Size - Statistics LibreTexts
June 24, 2024 - In reality, we can set whatever level of confidence we desire simply by changing the \(z_{\alpha/2}\) value in the formula. It is the analyst's choice. Common convention in Economics and most social sciences sets confidence intervals at either 90, 95, or 99 percent levels.
🌐
Wikipedia
en.wikipedia.org › wiki › Confidence_interval
Confidence interval - Wikipedia
October 29, 2025 - The confidence interval can be expressed in terms of probability with respect to a single theoretical (yet to be realized) sample: "There is a 95% probability that the 95% confidence interval calculated from a given future sample will cover the true value of the population parameter." This essentially reframes the "repeated samples" interpretation as a probability rather than a frequency. The confidence interval can be expressed in terms of statistical significance, e.g.: "The 95% confidence interval represents values that are not statistically significantly different from the point estimate at the .05 level."
🌐
Math is Fun
mathsisfun.com › data › confidence-interval.html
Confidence Intervals
Common choices are 95% or 99%. A 95% confidence interval means that this method would capture the true mean about 95% of the time if we repeated the sampling many times.
🌐
Calculator.net
calculator.net › home › math › confidence interval calculator
Confidence Interval Calculator
Calculator to compute the confidence interval or margin of error of a sample based on the desired confidence level. It also provides an error bar diagram.
🌐
Stat Trek
stattrek.com › estimation › confidence-interval-mean
Sample Mean Confidence Interval
Find the margin of error (ME). We use the margin of error formula to find the margin of error. ... Specify the confidence interval (CI). The range of the confidence interval is defined by the sample mean ... CI = 115 ± 2.1 And the uncertainty is denoted by the confidence level (99%).
Published   February 7, 2025
🌐
Statistics How To
statisticshowto.com › home › probability and statistics topics index › confidence interval: definition, examples
Confidence Interval: Definition, Examples - Statistics How To
June 26, 2025 - Microsoft Excel will return the confidence interval for the mean and the margin of error for your data. For this sample, the mean (Xbar) is 149.742 and the margin of error is 66.9367. So the mean has a lower limit of 149.742-66.936 and an upper limit of 149.742+66.936. That’s it! Warning: A 99 percent confidence interval doesn’t mean that there’s a 99 percent probability that the calculated interval has the actual mean.
🌐
Reddit
reddit.com › r/askstatistics › explanation of confidence interval in layman terms
r/AskStatistics on Reddit: Explanation of confidence interval in layman terms
November 7, 2023 -

How might you explain a frequentist confidence interval in layman terms? Say a 99% confidence interval with values 90 to 100. Not the definition, but the interpretation?

My thoughts go to if you produce 100 confidence intervals from random samples of the same population, 99 of those intervals will contain the true population parameter on average.

The actual interpretation I’ve learned from classes are “at the 99% confidence level, we estimate that the true population parameter is at least x and at most y.” I feel like I am missing something.

Any insight is appreciated.

Top answer
1 of 2
5
Your class interpretation is practical but technically wrong. Your initial thought is correct. We cannot draw probabilistic conclusions about the true value because it is fixed and unknown. We draw conclusions about the interval and we then extrapolate from that. Statistically all we say is that over repetitions of producing a 99% confidence intervals, 99% of them will include the true value. Now we lose our ability to speak about probabilities but we can still draw some logical conclusions. I have one 99% CI. It’s rather unlikely that I happened to pull the 1/100 that doesn’t include the population parameter. Therefore, this interval is a good viable range for the population parameter
2 of 2
1
The actual interpretation I’ve learned from classes are “at the 99% confidence level, we estimate that the true population parameter is at least x and at most y.” This can't be true. It's a probabilistic assertion about a number, not an event (possible result of an experiment). The parameters need to be identifiable for Frequentist Inference to be possible. In practice, that means a simple number, but more importantly, specifically excludes any probability. Your first interpretation is correct: if you produce 100 confidence intervals from random samples of the same population, you would expect 99 of those intervals will contain the true population parameter on average. It's important to emphasize that the methods that were followed have good probabilistic properties. In practice, one only gets one sample. My interpretation for a 99% confidence interval: According to the Statistic methods used to produce the following interval, we expect it would capture the value of the parameter in 99 out of a 100 possible experiments.
🌐
DataCamp
datacamp.com › tutorial › how-to-calculate-confidence-intervals-in-excel
How to Calculate Confidence Intervals in Excel | DataCamp
April 26, 2024 - Choose an alpha value that is greater than 0 and less than 1. Common choices are 0.05 for a 95% confidence level, 0.01 for a 99% confidence level, and so on. Remember that alpha is generally a smaller value since it’s obtained after deducting the confidence level from 100%. The #VALUE! error ...
🌐
Online Stat Book
onlinestatbook.com › 2 › estimation › mean.html
Confidence Interval for the Mean
Confidence Interval on the Mean · Help support this free site by buying your books from Amazon following one of these links: Naked Statistics: Stripping the Dread from the Data Statistics, 4th Edition Statistics For Dummies (For Dummies (Lifestyle))