p-value

  1. R

    Conceptual queries in modeling

    Hi all, I am from engineering background. I would require your help in certain conceptual questions in modeling. Your help would be greatly appreciated! Following are my few questions... (Pointers on these questions would help me , else you may direct me to any useful resources.) 1)If a...
  2. A

    Samples p-value in ANOVA

    Hi, my problem regards ANOVA: if the ANOVA test is sginificant (p-value<0.05), is there a way to calculate a p-value for each sample, in order to detect which is (are) significant different from the others? I know there are some post hoc tests, like Tukey or Scheffé, but they all compare...
  3. D

    Finding Significant Difference between Linear Regressions

    Hello. I have a scatterplot with two different sets of data plotted. Each individual set has its own linear regression formula and R-squared value. What type of test could I run on Microsoft Excel to get a p value to see if one dataset's trend is significantly different than that of the other...
  4. L

    Comparing two estimated distributions

    I estimated the density function (adaptive kde) from two samples (one of small size) and the cdf using approxfun() and integrate() in R. Now, I would implement a ks test to know if the two distributions are similar. I guess I have two options: Either, I draw two samples and use the function...
  5. S

    p value of the constant, can I ignore it?

    I'm analysing the influence of various factors on hare harvests in a specific are. E.g. How do the hare harvests change when the fox harvests increase. Term Coef | SE-Coef | T-Value | P-Value Constant | 415.0 | 28.7 | 14.46 | 0.000 Annual fox harvest | -1.054 | 0.193 | -5.45 | 0.001...
  6. C

    How can I get R to generate p-value when doing a correlation matrix?

    How can I get R to generate p-value for each correlation when doing a correlation matrix? Here are my current steps: > M <- cor(data1) # get correlations into Matrix > library('corrplot') # import corrplot library > corrplot(M, method = "circle")...
  7. X

    Urgent: Hypothesis Testing with unknown standard deviation

    Hi, I'm having a lot of trouble figuring out this problem without knowing the standard deviation. Please if anyone could help me that would be very much appreciated. Thank you! I also don't know how to calculate anything other than a 95% confidence interval. A national survey conducted in...
  8. H

    Find xbar - Hypothesis Testing

    I have a question I'm stuck on: You are given the following hypotheses: Ho: m = 34, Ha: m > 34 sd = 10 n = 65 What would the sample mean be for the p-value to be .05 We're on the chapter dealing with hypothesis testing, so I know I should be able to find the answer in here...
  9. G

    Significant p-value, but 95%CI includes 0

    Hello everyone, I have the following problem: The result of a Pearson correlation (sample size = 177) was significant, r = .127, p = .048 (one-tailed). However, the 95% confidence interval includes zero, 95% CI [-.02, .27]. How is it possible to have a significant p, when the CI...
  10. rogojel

    Mixing lasso with OLS

    Hi, I am looking at a data set of 45 continuous IV and 1 DV, trying to find an acceptable regression model. I tried the lasso with cross-validation and ended up with about 10 non-zero coefficients in the best model. However, when I ran the sanity test of building the OLS model with the 10...
  11. K

    how to measure p-value if dependent and independent come from different questionnaire

    I have in 1 dataset data from 1 questionnaire for students (which leads to the dependent: autonomy-score) and 1 questionnaire for teachers (which leads to the independent: autonomy-support-score). The independent is dichotomized in negative scores and positive scores. Can anyone help me...
  12. rogojel

    Confidence intervals vs. p -value

    Hi, we just had a very interesting discussion about the role of confidence intervals and p values in determining significance and I realised there is a point that is quite unclear to me, so, here is the question: I am considering a simple situation, a two sample proportion test, say. For each...
  13. K

    Significant difference between frequency of words in a text

    Hi, I guess it is a very basic question. Imagine two text samples, e.g. one text on someone's mother and the other on father. Text about mother includes word love for 80 times (1% of all words) and bout father for 50 times (0.8% of all words). Can we establish if this difference is significant...
  14. S

    Need help with medical study

    Hi, I'm writing a medical paper on asthma and I'm afraid I 've reached a point where I am unconfident of my statistics knowledge. I am hypothesizing that there is a relationship between elevated concentrations of a substance in the blood (we will call it X) and severity of asthma...
  15. R

    Can a relative risk and odds ratio differ in p-value?

    With increasing incidence of the outcome, odds ratios tend to overestimate relative risks. I was wondering whether they also start to differ in p-values. So my question is: could there be a situation where the (unadjusted) odds-ratio reaches statistical significance, but the (unadjusted)...
  16. R

    How to calculate p-value of two-sample t-test

    I have 2 independent data sets, and I know the following about each of them: mean, SD, and sample size. I calculated the t-statistic just fine my.t.test<-function(mu1, mu2, sd1, sd2, n1,n2){ t=(mu1-mu2)/sqrt((sd1)^2/n1+(sd2)^2/n2) return(t) } I know that the degrees of freedom...
  17. K

    p-value in a two-tailed hypothesis test

    how do i find the p-value of a two-tailed hypothesis test based on a large sample if I have a test staistic eqaul to 0.95
  18. S

    Model selection for logistic regression, comparing p-value approach, BIC and CV.

    Hi, I need to write a discussion on three approaches of model selection; p-value, Bayes factors (using BIC) and leave-one-out cross validation. The p-value is not preferred, statiscal significance depends on sample size, p-value is based on imaginary data, depends on the intentions of the...
  19. S

    p-value associated with Kruskal Wallis with multiple comparison?

    I have a data set that shows the differences between 3 different controllers of a biomechanical system on the same performance metric (specifically, I measure each controller's performance on a set of N tasks, and record the percentage of tasks that achieve success (i.e. the controlled segment...
  20. S

    calculating p-value from resampling of the null distribution

    Hi all, i am a PhD student in Bioinformatics and i'm dealing with some statistics issue in my reasearch; i was hoping you could lend me a hand :D I am dealing with a pool of datapoints (let's call it Q). I selected a subset of Q according to some particular characteristics, i will call...