confidence interval

  1. H

    Which statistical approach should be used to compare healthy and sick patients?

    Hello everyone, I'm stuck trying to figure out what the best strategy is for analyzing and distinguishing between healthy and sick patients. I have a dataset that was analysed with 20 healthy and 20 sick patients (each of them is different person). I collect data using one of the...
  2. S

    calculate the 95% confidence interval for the mean lead concentration for all the children in the school

    Please answer the following problem and provide a step by step explanation please The concentration of lead in the bloodstream was measured for a sample of 50 children from a large school near a busy main road. the sample mean was 10.12 ng ml and the standard deviation was 0.64 ng ml¯...
  3. S

    Essay Question

    Hello all, I have to write an essay at the moment and unfortunately I am stuck on a question, maybe you can help me with it. The question is as follows: "Describe in your own words how an approximation method that determines a confidence interval for the mean of a population from a sample can...
  4. T

    Computing Mean and Confidence Interval for an Unbalance Dataset

    Hello everyone, I am working on a project in which I am comparing a specific physiological value for a large set of species (75 Species in Total). One of the things that I wanted to do was to compute the mean and confidence interval of the data of all the species together, to show all the data...
  5. K

    Why does bootstraping with 50% samplesize and no replacements always gives appropriate confidence intervals.

    Hello, I compared different ways to calculate confidence intervals. On the one side I used the direct formular on the other side I used a percentile bootstrap methoden. (Calculate the statistic (e. g. mean) on n subsamples and choose the a/2 and 1-a/2 percentile for the confidence interval.) I...
  6. S

    Choosing the appropriate confidence interval for an odds ratio

    Hello everyone. I conducted an odds ratio test with a certain software, and I'm not sure about which confidence interval (CI) to use. The 2x2 table consists the distribution of counts as follows, by each cell: a=26, b=21, c=12, d=2. The output of the results included the calculated OR, with the...
  7. S

    Need help to correctly bootstrap confidence interval for correlation of 50 y-values against 50 averages from autocorrelated subsets of 2000 x-values

    I am helping out with some plots for a paper: simple X versus Y plots, and would like to provide some stats to improve the paper. My statistics knowledge is rusty and I am an R-noob with only a few weeks of Tidyverse under my belt, so I would appreciate some input. Am I on the right track? The...
  8. J

    Best way to say something about the accuracy of a measurement

    Hi, I'm an engineering student and encountered a problem to which I did not find a solution yet, and wondered if someone could give me the benefit of their expert opinion. I'm going to perform an experiment in which I'll cook an egg using standing electromagnetic waves, only for a short period...
  9. K

    Calculations for one-sided confidence interval

    Hello, I need help with understanding the result of µ*. Can someone show me the way to come to this result? Thank you in advance.
  10. E

    Can you Generating Meaningful Confidence Intervals from logarithmic data?

    Hi, could somebody with an advanced understanding of statistics please point me in the right direction? I have a question relating to the interpretation of confidence intervals generated from data demonstrating a logarithmic distribution on excel. As a disclaimer, this is 'getting into the...
  11. H

    Generalisation of 'overlapping confidence intervals'

    I had a question about a common (possibly incorrect) trend in the medical field to look at whether two 95% confidence intervals overlap as a sign of statistical significance at the 95% level. I'm aware this is overly conservative. I've heard that 83% confidence intervals are 'better' but not...
  12. T

    CI from normal distribution using indicator random variables

    Suppose that {X_1,X_2,...,X_n} is a random sample from N(m,1). Let I_i be indicator random variables such that it is 1 if X_i <= 0 and 0 otherwise. Calculate the 95% confidence interval for m. Suppose that sample is large enough.
  13. M

    What is the Confidence interval of this...?

    HI Friends, I've attached excel sheet having 19 records. Can you guys pls help me in finding 95% confidence interval for this. I tried finding it all way, but I'm not getting correct answer. Should t- distribution or Normal distribution be used..? I Thank in advance. Pls help me in finding...
  14. C

    Confidence Interval Problem

    So I have a target with X and Y coordinates. I find the minimum circle indicated by thick green line. I have the center to that circle X,Y. I get the distribution of the bullets from the X,Y position in Radius terms. What I want to do is predict the probabilty of them falling into the 90%, 95%...
  15. O

    Sample size and width of bootstrapped confidence intervals

    Hello all, I am looking for some help on confidence intervals calculated using the residual bootstrapping technique. For confidence intervals calculated according to multipling the t stastistic by the standard error of the mean, there is a clear link between the width of the interval and...
  16. I

    Sample Estimate expression in Brunner-Muenzel test with R (lawstat)

    Dear Talk Stats Community, I try to provide a reasonable interpretation of Sample Estimate expression P(X<Y) + .5*P(X=Y), which is shown as an output for BM-test in R (lawstat package). I am confused with the relationship between the following three probabilities: P(X<Y), P(X>Y), P(X=Y)...
  17. T

    Minimum Accepted Sample Size for Tolerance Interval (confidence interval)

    Hi, I'm using the tolerance interval function in minitab, my sample size is limited to 7 (the parts are expensive blah blah) I've heard to be statistically significant a sample size of 30 is recommended but in practice how low can I go for sample size when using a confidence / tolerance...
  18. H

    Difference-in-differences in Health Economics Research

    Hi, I'm doing a difference-in-differences analysis of a health policy intervention. Health clinics are paid for the percentage of eligible patients who they give the right treatment to. The clinics are measured/paid separately for each type of treatment indicator. One year, some of the...
  19. V

    T-testing of two samples(question about t-statistic)

    Hi have two questions regarding an t-test assignment i did. Basically the null hypothesis was that if sample x2 differed 35 off the mean from sample x1 was it reject-able? The mean of sample x is 395 The mean of sample ý is 435. So the issue is that i think the nominator for the t-statistic...
  20. F

    Constructing intervals VS hypothesis testing?

    Hi folks, let me briefly anticipate that I am a total newby to the magical world of statistics. So, right now I'm preparing for a "quantitative methods for economics" test, but while doing my exercises I found myself wondering about what could be very stupid things. here's the thing: I had...