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Questions tagged [p-value]

In frequentist hypothesis testing, the $p$-value is the probability of a result as extreme (or more) than the observed result, under the assumption that the null hypothesis is true.

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Are random variables sampled upon stopping rules exchangeable?

In this article from D. Berry https://www.jstor.org/stable/2684222?seq=1#page_scan_tab_contents the author uses an example to introduce some limits of p-values in frequentists analyses. He takes an ...
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How to compute multiple Chi^2 P-values for each of a factor in a 3-way contingency table?

How were the p-values calculated using chi^2 (method cited in paper below) in the following table. Its a three way contingency table, tumor stage 1-4, race B/W and hospital city/university. They have ...
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What to do when variance increases with sample size

I have a large dataset that has been compiled from 6 surveys. The values are how much of a food additive is used in a particular food. After breaking the additives into pre-established groups, I am ...
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What does “Scientists rise up against statistical significance” mean? (Comment in Nature)

The title of the Comment in Nature Scientists rise up against statistical significance begins with: Valentin Amrhein, Sander Greenland, Blake McShane and more than 800 signatories call for an end ...
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Negative P-Curve Analysis output

Data set I put following values into the p-curve app. Light gray values were not supported by the p-curve analysis. I'm not sure if this studies should actually be sorted out (because of very small p-...
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How important is a statistically significant intercept?

I've created the following model: log(consumption) = a + b*log(GDP) + c*log(GDP(-1)) + d*log(consumption(-1)) The slope coefficients are all statistically ...
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My P-value Manually Calculated is Different from when I use the Prop-Test, in R Studio

Trying to calculate the p-value manually and then demonstrate it using the Prop test but I keep getting different P-values. ...
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38 views

P-Value in Shapiro-Wilk test

I've read that if this p-value is less than 0.05 (for a 95% confidence interval), the null hypothesis that the data comes from a normal distribution must be rejected. However, in the following ...
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Disagreement between p-values and bias corrected CI in path analysis

I am conducting a path analysis that include estimation of indirect effects (i.e. mediation). For each indirect effect specified in the model (a1*b1), I have both a p-value and a 95% boostrapped CI. ...
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Computing a p-value using the ratios of the means and ratios of the variances

When you have a ratio of the means ($\mu_1/\mu_2$) and ratio of the variances ($\sigma^2_1/\sigma^2_2$) from two distributions, how can you compute the p-value telling you whether the means of the two ...
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Knowing the P values of my objective function [on hold]

I used a fmincon function to solve my model equation (K2) which is depended on three unknown constants. I know the values of K2 experimentally, so accordingly I able to minimize the output values of ...
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P-Values in Wilcoxon test

I have a question that if a p value less than 0.05 in wilcox test means that the two data are significantly different and the p-value of 1 means that are exactly same, then what is the meaning of a p-...
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Different p value of two different function in R while computing Cramér-von Mises test

When I tried to run Cramér-von Mises for generalized extreme value distribution in R, I got different p value for cvm.test function and gnfit function. The difference is quite significant like 0.07. ...
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Test statistical significance with small number - Fisher's exact test

Before the part of the question related to the title, here is some background: I'm build a model that tries to predict a binary outcome ($Y$), given a set of features. Some of this features are ...
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1answer
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Dummy regression - p-value interpretation

Suppose I want to predict the quality of an essay as a function of how many essays a person produces in a year. Something like this: $quality = m_{0}\ (quantity/year) + k$ in which, $m_0$ is the ...
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How to understand pvalue with controls/covariates

Suppose I have a study with a response variable $y$ and two explanatory variables $x_1, x_2$. I do a regression such as lm(y~x1) and get a p-value of $p_1'$ for $...
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Statistics Homework Help [closed]

Not sure how to tackle this question, can someone help me? A team of medical researchers carried out a study among swimmers to investigate a possible link between exposure to chlorinated swimming ...
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Removing coefficients from multiple regression analysis

0verview I am undertaking a study where we analysing the fine details of two multiple regression equations. Multiple regressions were carried out for the months of February and August 2017, with ET ...
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p value in backward elimination regression

I need some help with the backward elimination output from Minitab below. Can p values A, B, C, D be equal to 0.745? Or the p value should be smaller than 0.745?
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What is the closed form or analytical expression of the distribution of p-values, if we *don't* test point Null hypotheses?

Problem If we test a true point Null hypothesis using a continuously distributed test statistic, it is possible to prove that the $p$-value resulting from such test is a realisation of a uniform ...
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prop.test alternative usage for differences test

I have a following matrix mat of successes: 50 24 46 36 and want to perform a 2-sample test for equality significance with <...
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1answer
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Evidence for man-made global warming hits 'gold standard': how did they do this?

How should we interpret the $5\sigma$ threshold in this research on climate change? This message in a Reuter's article from 25 february is currently all over the news: They said confidence that ...
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What are reasonable decisions to make when performing logistic regression along with validation?

I'm not really a statistician but, in the words of Scarlet O'Hara in Gone with the Wind, "have always depended on the kindness of strangers.” I have a data matrix corresponding to 20 trials with 15 ...
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p-value for univariate analysis

So I am reading an article in which it has a table showing p-values and hazard ratios for what they say is "Univariate and multivariate analyses of clinical and treatment factors potentially ...
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2answers
34 views

Appropriate statistical test for data which do not have normally distribution and do not have equal variance

My data has 150 samples and is not normally distributed, and it does not have equal variances either. I know t-test (e.g. this python method) can be used when data is normally distributed and it can ...
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1answer
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Cohen's d vs. p-value

I recently started reading Evidence Base Update for Autism Spectrum Disorder. In Table 4 they present a summary of previous work. They use Cohen's $d$ values. From here : $d$ = $|\frac{M_{1} - M_{...
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treatment and sum contrasts, inconsistent results

I am fitting a linear mixed effect models with two factors (mPair with 6 levels, and spd_des with 3 levels) and their ...
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can one calculate a p value in a distribution [closed]

I have an event which happens so many times, I want to know how significantly is 1300$ in comparison to the distribution. which test should I use ?
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Can Bayes factors be an alternative to multiple comparisons corrections?

I am currently using p-values and Bayes factors to interpret my results. I have multiple comparisons so was going to perform a Bonferroni correction, however I am hesistant due to its highly ...
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1answer
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Cause and Effect of one variable on another in python

I have a blog data set, which has essentially many columns such as: ...
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1answer
62 views

How to interpret p-value? [closed]

Let’s consider a example: $\text{Pr}(H_0 \text{ is true}\mid\text{reject } H_0)$. This has a direct, simple meaning: it’s the probability with which we should believe $H_0$ is false given that we ...
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1answer
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Why there are two p-values for the F value, one from Summary and others from ANOVA?

Consider the 'estandar' output of R that I copied from Anova from R output interpretation and added other variables. Why there are two p-values? One from Summary ...
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1answer
35 views

p-value adjustment for correlation matrix

Suppose I have a large number of features, and I want to figure out which of them (if any) are "significantly" correlated. In short, how I can estimate significance in a way that appropriately ...
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1answer
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how to present results for two group success rate with confidence interval

I have two groups A and B, and for each data point I have two possible outcomes, success and failures. For each group, I have calculated the success rate, and the confidence interval for a binomial ...
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Welch's t-test false positive error rate challenge

It is well known that Welch's t-test is robust to violations of the normality assumption and is arguably underused by researchers.1 It is, of course, the default t-test in R. In terms of containing ...
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Computing the Sample Size for the sum of Bernoulli RVs with different probabilites times a constant

I have the following statistic for which I need to figure out a sample size: $$S= \frac{1}{n}\sum_{i=1}^n \left(c_i+\sum_{j=1}^{100} b_{ij}X_i\right)$$ where $c_i$ and $b_{ij}$ are constants and $...
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2answers
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Simulating optional stopping in data collection with respect to p values

In null-hypothesis significance testing, if we were to optionally stop data collection every so often and check the p value on the data, the null hypothesis may be eventually be rejected even when it ...
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When the distribution is known, should I use t-test or z-test for testing the significance of Pearson Correlation Coefficient?

Generally speaking, t-test is used for testing the pearson correlation coefficient significance of X's and Y's. In my case, however, assuming X and Y both follow some known distributions. I have a ...
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Calculating P-value for multivariate normal distributions?

I'm given a set of 500 ($\sigma_i, \mu_i$) that define a 500-dimensional multivariate normal distribution, where each dimension is effectively independent from all the others. Given a 500-...
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Non-uniform p-values from hoeffd function in Hmisc when data sets are independent

When using the function hoeffd in the CRAN package Hmisc I get unusual p-values for pairs of data sets that are independent. The function hoeffd is an implementation of Hoeffding's $D$ statistic. ...
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1answer
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Combining the conclusions from multiple Diebold-Mariano tests

Suppose I have two forecasting models, A and B. Moreover, suppose I have multiple datasets and I use each of these sets to perform Diebold-Mariano tests. My aim is to find out which of the two models ...
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1answer
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Null hypothesis for individual coefficient's p-value in multivariate logistic regression

When calculating $p$-values for individual coefficient $a_i$ (for variable $X_i$) in a multivariate logistic regression, is the null hypothesis that all $a$'s are zero? that $a_i$ is zero and others ...
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1answer
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Is chi-square meaningful for such a small data set?

I write about stats for a lacrosse web site. Most teams play one game each week, but now and again a team will play two games in a weekend. I'm looking into whether they are more or less likely to win ...
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1answer
20 views

What is the proper way to report test statistics used in a permutation analysis?

In my paper, I run some ANOVAs and t-tests, and the test statistics are F and t respectively. I have reason to believe the null distributions are not normal, so I have run permutation tests and ...
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How to adjust p-value for slow features?

I have some monthly, weekly and daily features. I want to do regression against a daily target. I use locf to fill monthly/weekly features. Also I have some moving ...
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2answers
79 views

Kolmogorov Smirnov Test Calculating the P Value Manually

So I'm trying to calculate the p value for a KS Test across some score data. I am using a variable called bad that is either 1 or 0 that splits the data into 2 samples effectively. I have run in SAS ...
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2answers
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I can't get a p-value higher than 0.05 with R [closed]

I'm following the Pizza example from here: https://www.dummies.com/education/math/statistics/what-a-p-value-tells-you-about-statistical-data/ ...
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Is the critical t-statistic value always 1.96 for the standard normal distribution? [duplicate]

I am running a regression model and assume that all my variables are following a standard normal distribution. From this model I am getting the value of the coefficients of the predictors and their ...
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Post hoc for wilcoxon multiple tests

I have a database of brain MRI acquisitions of 20 subjects at two time points. I have elaborated the signal with multiple models. For each model, I have estimated 4-6 parameters maps. At the moment I ...
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Multiple comparisons correction in between-subject classification analysis

I am working with a dataset of 46 subjects (23 controls and 23 patients) fmri brain t-maps each with 4 experimental conditions. The main purpose of my analysis is to find the highest classification ...