An interval of random variables, depending on observed data, which, with a fixed probability, contain an unknown parameter of interest.

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14 views

How do I calculate the Confidence intervall for the regression coefficient? [duplicate]

Hello! I need to calculate the 95 percent CI for the regression coefficients (coef). Is it possible to simply do this by taking the values plus or minus 1.96 times its standard error (se(coef))?
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21 views

Determine significance of an observed continuous distribution given many randomly generated continuous distributions

Suppose there is a vector, v, that contains the body height of every person over 30 years old on earth. It looks something like this: ...
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1answer
41 views

Confidence intervals for group means (R)

Here are some sample data in R: set.seed(42) df <- data.frame(g = factor(rep(1:2, each= 50)), y = rnorm(100)+rep(0:1, each=50)) One can easily get group means ...
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8 views

1-Sided Lower Confidence Level Concept for Reliability

For reliability (R) engineering discipline, reliability of an item is the conditional probability that the item will be functional within the mission duration at a given confidence level. so ...
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13 views

Statistical test for relationships when many samples are unknown

I'm fairly new to statistics - I'm sure this is a basic question but my google searching is failing me. Happy to just be pointed to other reading. I have 3 datasets of varying sizes (N1 ~ 200,000, N2 ...
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5 views

How to find confidence interval for the mean of a variable between two different factors in SPSS?

I have data that outlines tumor sizes in patients and whether or not they are male or female. I would like to find the 95% confidence interval for the difference in mean tumor size between male and ...
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6 views

Given Pivotal Quantities Find Confidence Limits

Based on the pivotal quantities below $Q_{1} = \frac{ \hat{\theta_{1}} - \theta_{1}}{ \hat{\theta_{2}}} , Q_{2} = \begin{pmatrix} \frac{\hat{\theta_{2}}}{\theta_{2}}\end{pmatrix}^{-1}$ ...
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11 views

Confidence interval for fitted lambda from Possion distrubtion

So my question is: you are given a set of data and you know the distribution is Possion with parameter lamda > 0. I figure out xbar is 4.06, and the z value we are using is 1.96 and n=50? But how can ...
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16 views

How many boxes have balls?

I have N boxes, each of which may or may not contain a ball. I want to know how many boxes have balls by sampling the boxes in the following way. For each box in the N boxes: I open this box with ...
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20 views

I have 5 models and each one consists of two 95 % confidence intervals, one for each axes, how can I plot these in R (ggplot2)? [closed]

I have 5 models and each one consists of two 95 % confidence intervals, one for each axe, how can I find and plot these in R (ggplot2)? I tried to put the data in an ascending order and find them ...
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16 views

How to get 95% CI from R's coxph? [migrated]

I have used the following function in R's coxph() to fit a cox hazard model. I want to report the proper statistics; however, there is no 95% CI in the output. ...
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16 views

alternative to the delta method for computing the variance & CI of products of probabilities

I'm trying to find a way to calculate the confidence interval of the product of probabilities without using the delta method or Program MARK. I am using a logistic-exposure model to estimate the ...
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12 views

applying stats to ratings of products

Which should I trust more, a 4.5 stars rating with 46 votes, or 4 stars with 66 votes? This isn't Amazon where I can look at the distribution. Can I treat this like a binomial confidence interval? ...
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2answers
39 views

How to interpret R Pearson's correlation test?

I am trying to learn a bit of R and statistics so as "toy project" I have started from the famous Iris dataset (150 rows, 3 classes). I have applied to two features the "correlation test" in this way: ...
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16 views

Best approach for calculating confidence score (p-value) - for Bayes models

This is a generic question on the best approach for giving a p-value to a "most likely" solution given by a graphical Bayes model. I am building a graphical model in Stan, for finding the most likely ...
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2answers
40 views

Why is confidence width narrower, when sample proportions are smaller?

I am using a binomial distribution to calculate confidence intervals around a proportion. I noticed that for a fixed sample size, the width between the confidence intervals gets narrower as the ...
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8 views

Could anyone teach me how to calculate the 95% Confidence Interval for a Geometric Mean Titer Ratio?

To help teach me I have provided data from 4 separate experiments that were previously analyzed (listed at the bottom of this post). I was able to figure out how to calculate the Geometric Mean Titer ...
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1answer
46 views

P-value & Confidence Interval…I choose you CI!

I'm struggling with an interpretation of p-value and confidence interval. They are both in agreement, but yet, can't be used together to make one statement about population proportion. So...am I ...
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18 views

Problems when bootstraping confidence interval for panel data-labor economics

I am currently leading a research project on labor economics. But I met some problems with bootstrapping the confidence interval. What I want to do is to find how moving will influence workers' ...
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1answer
30 views

Estimating normalization constant with Monte Carlo integration

Be $f(x)$ a function. Suppose that $f(x)$ integrates to a finite value $k$: $$\int_{-\infty}^{\infty}f(x)dx=k$$ The normalization constant of $f(x)$ is $1/k$. Monte Carlo integration can give an ...
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1answer
27 views

Get a 95% confidence interval for Cohen's Kappa in R

I've got a study with two radiologist's reading chest x-rays and want to calculate Cohen's kappa of their agreement. The kappa2 function in the "irr" package and ...
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1answer
39 views

When confidence intervals of two parameters do not overlap with the mean of the other, why is it considered to be statistically significant?

Consider two parameters with means A and B with 95% confidence intervals. If the confidence intervals of the parameters do not overlap with the mean of the other, why is it considered to be ...
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1answer
32 views

Confidence intervals and standard error for binary data/proportions

I'm doing some research into degrees held by professionals of different types, based on survey data. I'd like to be able to provide confidence intervals for some of the subgroups of professionals as ...
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29 views

Confidence Interval using likelihood-ratio statistic

The lifetime $T$ of a light bulb follows a distribution with probability density function $$f(t;\theta) = 0.5\theta^3t^2e^{-{\theta}t}$$ If $n = 20$, $\sum_{i=1}^{20} t_i = 996$ Determine the 95% ...
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11 views

Equal Precisision confidence band not getting sufficient coverage [closed]

I'm looking at confidence bands for the survival function of right-censored data. In particular the Hall-Wellner band and the equal precision band (by Nair). Using the km.ci R package I did a ...
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1answer
44 views

odds ratio vs confidence interval in logistic regression

What is the relationship between the confidence interval and odds ratio of a regression coefficient in multivariable logistic regression? Is there a one to one relationship? i.e. Can I measure one ...
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8 views

individual differences between two paired populations

I have two sets of data A and B each with n=80. For A and B a measurement was taken in a different condition and the data are paired. I know there is a difference between the whole populations of A ...
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26 views

A/B Testing: Is it necessary to test old versions every now and then?

Recently I was talking to a coworker about A/B Testing -- we run a variety of A/B tests on our website and the thought of doing a "back test" was mentioned where we essentially restore an old design ...
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1answer
82 views

Find data and confidence “ellipses” (regions?) for a bivariate median?

I'm wondering about ways to compute data and confidence ellipses around a bivariate median. For example, I can easily compute a data ellipse or a confidence ellipse for the bivariate mean of the ...
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2answers
120 views

Confusing confidence interval question from old textbook

Lets say an investigator reports a 95 percent confidence interval of 1 to 23 dollars per month in reduced utility bills for a randomly selected group of 50 customers who underwent training in ...
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10 views

Standard error of mean for overdispersed count data

I have count data from survey transects at several sites (typical n ~10). I am interested in whether the sample mean exceeds a threshold at [1-alpha]% confidence level (...knowing I have low power), ...
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16 views

Statistical analysis of the results calculated from a stochastic global optimization

I recently use the Basinhopping algorithm [1], a Monte Carlo Markov Chain variant, to find the global minimum of numerical functions (which are not necessarily smooth). Though the global optimization ...
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2answers
42 views

95% Confidence Interval for Proportions in R

How can I calculate a 95% interval to estimate the actual proportion of SUV's in the city in R? I would like to calculate the interval on this data: ...
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1answer
64 views

Conclusion from Hypothesis Testing and CI

Can you draw a conclusion from combining results of hypothesis testing and confidence interval? For example, here is a fictitious hypothesis test for 1-proportion: Ho = p ≥ 90% Ha = p < 90% ...
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1answer
39 views

How to work out 95% confidence interval from odds ratio and standard error

$lnOR = -0.909 - (-1.707) = 0.798$ and its standard error is $SE(lnOR) = \sqrt{0.2182 + 0.3182} = 0.386$. The results of the adjusted indirect comparison suggest that x was less effective than y for ...
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21 views

Confidence Intervals of a one sided truncated normal distribution

Assume $y\sim N(\mu,\sigma^2)$ it can be shown that UMP alpha ($\alpha$) level tests are derived from the $\alpha/2$ quantiles i.e. $z(\alpha/2)$ How can we find confidence intervals of a truncated ...
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74 views

Testing difference between two portions of a time series with Chebyshev Theorem

I have a time series which presents two different patterns during time. These patterns are related to two different events that happen during the experiment. I can manually select the temporal ...
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30 views

Population Proportion Confidence Interval

Looking at the equations for confidence interval and sample size estimation of population proportion, I don't understand why population size isn't a factor. Can anyone explain? Thanks! $$ \hat{p} \pm ...
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19 views

How to get SAS to output odds ratios for main effects in a Firth logistic regression featuring an interaction term

Data for this question SPSS file type: SRFULL2.sav Dropbox share link - note you can import it into SAS, which I am using for my analysis here. My SAS-run model is such that: ...
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26 views

Hypothesis Testing Fictitious Study Help

I'm doing a self-study on hypothesis testing and have created a fictitious study to facilitate my learning. I just need validation, from you experts, that my thought process on the concepts and ...
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9 views

Does a confidence interval for an estimator allow me to evaluate a hypothesis? [duplicate]

Let's suppose I am surveying $n$ democratic citizens about whether they will vote for Candidate A or Candidate B. Let's suppose my survey yields $x$ for Candidate A and $n-x$ for Candidate B, $x \in ...
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1answer
31 views

Compute confidence interval for univariate Kernel Density Estimator

I've got a univariate dataset (timeseries) for two kind of simulated systems, and I want to explore the differences between the two. To do that, I can build a univariate gaussian KDE for each dataset ...
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22 views

How to conduct experiment for binomial confidence interval?

I'm learning confidence intervals and want to prove that they work using experiments. For example to test confidence interval for the mean I've constructed the following function in python: ...
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1answer
37 views

Confidence interval for MLE estimator?

I have an MLE estimator which is asymptotically normally distributed with mean $\beta$ and variance $\beta^2/n$. How do I get an approximate confidence interval for this estimator? I know usually two ...
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34 views

Chi-square testing with demographic data viable to compensate non-response bias?

(Hello CrossValidated, first poster here, so please have mercy with any transgressions of mine!) For my thesis, I am currently researching the correlation between stance to organizational change and ...
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16 views

R output for confidence interval

I have been doing confidence intervals in R and my output is similar to that of the question I attached. I thought confidence intervals were supposed to my symmetric about the point estimate however ...
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22 views

Confidence interval for estimator of the mean of different binomial distributions

I have a dataset that is a series of binary matrices like so: 00000 01110 00110 00000 Each matrix is sampling from the same distribution. I'm aggregating the 2D ...
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1answer
20 views

How to interpret Monte Carlo samples of the ratio of two variables?

My aim is to find the 95% confidence interval of the ratio of two variables for which I have summary statistics. More specifically, I have the prevalence of mothers drinking during their pregnancy ...
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26 views

What does overlap of bootstrap means 95% confidence interval dotplot infer?

@FrankHarrell has suggested that “A good nonparametric approach to getting confidence intervals for means and differences in means is the bootstrap.” That said, my question is how to interpret ...