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Questions tagged [confidence-interval]

In statistics, a confidence interval (CI) is a type of interval estimate (of a population parameter) that is computed from the observed data.

The confidence level is the frequency (i.e., the proportion) of possible confidence intervals that contain the true value of their corresponding parameter. In other words, if confidence intervals are constructed using a given confidence level in an infinite number of independent experiments, the proportion of those intervals that contain the true value of the parameter will match the confidence level.

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How do I find the confidence interval? 2 sample t-test

Specifically, the last question on this page. I do not know how to even get started. I have tried using an online calculator, but that did not work, and none of my course notes indicate how to solve this. I do not even know what the name of this…
Daniel Paczuski Bak
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Conditional probability explanations. One is wrong and one is right. What's the difference?

I've read this before and I'm still confused at the difference... can someone make it intuitive? In my textbook, this is written: The correct way to speak of confidence is intervals is to say: 'We are XX% confident that the population parameter…
Jwan622
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Trial until first success. What is p?

Let's say I repeated some trial 90 times and got a success on my last attempt. I guessing that such a confidence interval is different than if I had gotten 1 success at any point out of my 90 trials. In my case I didn't decide on 90 trials…
Simon
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Algebra with variables having confidence intervalls

In my work I have come across a situation where I need to derive values from values having confidence intervalls. I want to calculate the confidence intervals for my derived values. I am quite rusty when it comes to performing math but I seem to…
jonalv
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what's the consequence/meaning of using estimate for mean/std when calculating confidence interval?

I understand https://math.stackexchange.com/a/192910/291153 and I could rephrase it something like : The true mean is likely to fall under the confidence interval x% times if we do the experiment many times. But isn't the statement true only when…
eugene
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Choosing options based on the given information regarding the confidence interval.

Let $X_1,...,X_n$, $n\geq5$ be a random sample from a distribution with the density function: $f(x,\theta)= e^{-(x-\theta)}$ where $x\geq\theta$. Then, which of the following statements are correct: A $95%$% confidence interval of $\theta$ has to…
userNoOne
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Confidence Interval clarification

I just started learning confidence intervals and I read online the definitions of a confidence interval. Defn 1: http://stattrek.com/statistics/dictionary.aspx?definition=confidence_interval Defn 2: My notes Now, I feel as if those two are…
Twenty-six colours
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Why is this the wrong way to interpret a confidence interval?

The General Social Survey (GSS) is a sociological survey used to collect data on demographic characteristics and attitudes of residents of the United States. In 2010, the survey collected responses from over a thousand US residents. The survey is…
Jwan622
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Maximum error in confidence interval

A sample of $40$ cows is drawn to estimate the mean weight of a large herd of cattle. If the standard deviation of the sample is $96$ kg, what is the maximum error in a $90\text{%}$ confidence interval estimate?
user3784813
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sample mean to population mean

How to use sample mean to know the population mean? Now I have sample mean, sd and population mean. They are 37.28, 25 and 34. Sample size is 25 Here is my thought N < 25. Sample mean may not equal to population mean. population mean is 37.28 +…
Nobi
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How to calculate this confidence interval?

I numerically integrate a differential equation of the form $y’ = f(y, a, b)$ where the parameters $a$ and $b$ are real numbers. Also, I have many real numbers $v$ from $v_1$ to $v_m$ ($m$ is around 5000 to 6000) and a few $b$'s from $b_1$ to $b_n$…
Cristiano
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Wilson interval estimation for multiple classes (confusion matrix)

Sorry to resurrect this, but after 9 years the links mentioned here (How can the Wilson Confidence Interval be adapted for more than 2 outcomes?) went dead ;) I am looking for similar help in adapting the interval to multiple categories,…
StephanT
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How to calculate the confidence interval of non-normal large volume data sample?

There are tens of thousands of data, and the sample mean is 5.04, the sample standard deviation is 3.97, the skewness is 3.74, and the kurtosis is 23.721. How can we calculate confidence intervals for such non-normal large volume data samples to…
Puyinn
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Confidence interval containing $X_{(n+1)}$

Sample size $n+1$, sample mean = $X_{bar}$ (size = n), sample deviation = $S$ (size=n) How can we calculated confidence interval with 95% confidence, containing $X_{(n+1)}$ ? If $E(X)=μ$, then $CI$ for $μ$ is $X_{bar} - t*S \sqrt n$, $X_{bar} +…
hyemin ju
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Interval for a lower limit of a $0.95$ confidence interval

Olive oil is bottled. The filling quantity is normally distributed. A sample of $n=27$ bottlings had a mean value of $198.3$ ml and a sample standard deviation of $10.3$ ml. I would like to find the lower limit for a $0.95$ confidence interval for…
Slim Shady
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