# 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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### Calculate p-value from a variance of a correlation matrix

I do not know where to start with this. I want to find if the correlation is significant between taste and looks. I have a matrix as such: good ok bad good 19 10 9 ok 12 19 7 bad 7 9 22 where ...
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### Chi square interpretation

Hello what does u value mean in this table, what does it indicate? This is Mann Whitney test
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### Interpretation of kruskal wallis test results

Hello I have run a kruskal wallis test to compare the median between three groups as in this picture below: I know what median value and p value are but: IQR is the spread of data but what is used ...
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### How to interpret high P-value and low Mcnemar's Test P-value in Caret R?

I am using the caret R package to evaluate machine learning models. This gives me a lot of information about different metrics. I am confused about my result why ...
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### Why can't we use AIC and p-value variable selection within the same model building exercise?

In our assignment we were asked to model the compressive strength of concrete (response variable: Strength) with predictor variables Cement (kg/m^3), Water (kg/m^3), and Coarse.Aggregate (kg/m^3). We ...
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### Adjust p-value of the all output or just the variable of interest?

I am running linear mixed effect models using the lme4 package in R with the following output. ...
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### How to report a P-value?

I am writing the results of my thesis, and I have a few questions on how to report P-values. When is it appropriate to give the exact P-value, instead of writing e.g. P<0.05 (also in case of non-...
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### What does it mean if my confidence interval includes zero with a significant p value in linear regression analysis?

I performed linear regression analysis to assess the associations between continuous variables. I found a significant p-value but my confidence interval includes zero. What does it mean? Here are the ...
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### Comparing scientific studies (p-values, q-values)

I am comparing two studies. Each study consists of an affected (cancer) and control groups of patients, for which a number of biomarkers (gut microbial species) were studied. For each biomarker ...
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### Statistics And Probability [closed]

The Audit Team of ABC University claims that the mean monthly salary of the teachers is Php18,000.00 with a standard deviation of Php4,500.00. A researcher takes a random sample of 20 teachers and ...
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### How to test overlapping confidence intervals to see a significant difference between groups in a COX propotional model

Cox proportional models have been done with this result. The two groups (C, B) had overlapping confidence intervals, while the p-value was significant at p<0.001. I have used this code to get the ...
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### How to calculate the statistical significance of the difference in a categorical value of two populations?

There has recently been a statistical report regarding whether Cypriots are ready for a female president. There was a difference in the opinions of men and women and I'm wondering if it is ...
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### Effect of size of data on the confidence on the coefficients in Linear regression? [duplicate]

What is the impact of size data on the confidence (p-value) of model coefficients?. Does increasing the size of data always improve the confidence in the model coefficients? Suppose I have 100 data ...
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### T-testing on sparse data

Problem: I have two stochastic processes, $S_1$ and $S_2$, that frequently are zero, but occasionally have positive values with unknown probabilities $q_1$ and $q_2$. e.g.  S_1 = \{0,0,0,0,0,21,0,0,...
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### Test uniformity after adding some non-uniform data in python

I generate N1 numbers from uniform distribution using numpy python package from a certain interval e.g., ...
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### If p-values are random, why not decide using the test statistic instead?

I am currently reading the paper Duncan J Murdoch, Yu-Ling Tsai & James Adcock (2008) P-Values are Random Variables, The American Statistician, 62:3, 242-245, DOI: 10.1198/000313008X332421 In ...
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### calculating expected value of false discovery rate - Benjamini-hochberg

I recently got a question that cannot seem to solve, as a beginner in the statistical field. assume we have 20 tests. 5 with the p-value of 1/330 5 with the p-value of 1/150 10 with the p-value of 1/...
1 vote
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### Is this interpretation of the relationship between p-values and type I error rates correct?

I am trying to check my understanding of the relationship between p-values and type I error rates. I am going to use the following example to do so, so I would appreciate any feedback on it. Suppose ...
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### Do the p-values produced by lmerTest::lmer need to be adjusted for multiple comparisons?

I am running a fairly simple linear mixed model with multiple observations per patient, comparing a lab value to a reference group (healthy control). Here's some fake data: ...
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### p-value calculation for coin flipping

Here it mentioned we need to take into consideration of rare and rarer event (up to 12:28) for p-value calculation. There is a problem: You observed 3 sequences of 5 flips of coin with at least one ...
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### Correlations significant at individual level, but not at group level?

For my research I have to do correlation tests to see how different measures of animal welfare are related to each other. When i run the test using the data at individual level, it shows a weak ...
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### How to correct Chi-square's p-value when working with very unbalanced contingency tables?

I'm studying the association between a rare disease and smoking. Because the disease is rare, my contingency table is highly unbalanced with way more Non-Diseased than Diseased individuals, ...
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### Should p.values be adjusted when comparing correlations of differently sized groups?

I have performed a series of correlations between several variables (all of them are continuous). Some of these correlations were conducted with the entire sample (which is composed of two independent ...
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1 vote
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### The p value of my OPLS-DA model was -nan(ind), I don't know, what's mean, and the residual MS was infinite, I need help here?

I obtained for the first time strange cross-validation results of my OPLS-DA model, the CV ANOVA was -nan(ind), SD residual was inf, MS residual was inf also, moreover, F test equal to zero. The ...
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### How to set up a p-value based significance testing (example experiment is given)

I am a software engineer performing a real-life A/B test, and I wanted to use conventional statistical tools to make sure my results were statistically significant. I have some basic textbook ...
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### why the p value changes when I run a linear mixed model instead of a simple regression? and how random effects affect the output?

I ran two models, a linear regression model and a linear mixed model, I did this because I was suspecting that there were some levels or hierarchy in my data, specifically in my subjects and ...
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### Serial mediation Hayes Process 6 with SPSS; 2 mediators - issues with paths a1 and a2

I have the following issues which I would like to understand: I have recently run a Hayes Process 6 analysis. I have checked for outliers (Mahalanobis, Cook's and Leverage and excluded cases that did ...
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### Find type I and type II errors for t-test using p-value analysis

Say I have some social network's logs, containing $\textit{views}$ and $\textit{likes}$ data (i.e. those are vectors). We would like to make some investigation of accuracy and power of the tests. We ...
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### How to correctly analyse a reduction in variance, and a trend towards a desired value over time?

I have a dataset consisting of some integer values collected over a series of five games, and was hoping someone might be able to recommend an appropriate test to determine whether: the interquartile ...
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1 vote
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### What to do when the p-value is not significant?

What can I do when the p-value of my regression is not significant? I tried to transform it with log or sqrt, it improved a little, but not enough to go below the 5%. The residuals follow a Normal ...
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### Understanding the relationship between a 'sampling distribution of a statistic' and a 'population distribution' in the context of a 'hypothesis test'

I would like to confirm that I am understanding the relationship between a sampling distribution of a statistic (an example of a 'statistic' would be a sample mean $\bar{x}$) and a population ...
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### true or false (p<0.05)

Can someone with more experience explain this statement to me? If one, with a hypothesis test, tests for equal means in two samples and gets the result p<0.05, does this imply that the ...
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1 vote
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### Differences between P value and confidence interval for calculated OR

I have returned to a piece of work and was re-running some statistical analysis. I found differences in the P values (which is > 0.05) and OR confidence intervals which was greater than 1. Is there ...
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### Several p-values and understanding real relationships

I am trying to solve following exercise: Suppose I have 500 chemicals for affecting the bacteria growth. My null hypothesis is that applying chemical or not doesn't have any effect on bacteria growth. ...
1 vote
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### Help me find (ok, calculate/approx/uncover) the p-value in the following tables

For a meta-analysis I am looking for the p-values in these tables derived from reports dating back to 1980... I am, by now, pretty sure I can't but maybe there is someone smarter than me here... If ...
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### Relationship between regression coefficients in regression vs. reverse regression (with controls)

Question: How do the coefficients in a multiple linear regression (Regress y on x and controls Z) relate to the coefficients in the reverse regression (Regress x on y and controls Z)? Simple Linear ...
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### p-values of standardized vs non-standardized regression model coefficients - are they the same?

I made the following simple regression model and used stargazer to output a table that plots the standardized vs non-standardized regression model coefficients. ...
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### Comparison of two methods which use confidence interval for testing

I have a parameter, which I want to test whether it is different from 0 or not. Using a sample, instead of using p-value, I have constructed two confidence intervals, say CI 1 and CI 2 based on two ...
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### when to reject a hypothesis, size and p-value

When explaining the reason for rejecting a null hypothesis, I sometimes see "p-value is small", and sometimes it's "for a test of size $\alpha$, we reject it when (some condition)"....
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### What is the general right call to make from a marginal difference in A/B test results in recommender system?

This was one of the business-related questions from my technical interview last week for a data science position in a recommender system team at a search engine company focusing on advertisement ...
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1 vote
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### Correlation between binary variables

Long story short - I am lost among the ways to check for relation (whether there is any) between binary variables. Context - I am working on a side project where I try to analyze marketplace data and ...
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### Can I use zscore to calculate pvalue of coefficients in polynomial regression model?

Recently I am trying to reproduce results from this paper. The author performed microassay to detect gene expression in mutiple overlapping time window. Take time window 1 for example, let's say there ...
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### Basic Statistics: Difference between P-Value and Alpha?

I have always considered myself decent at basic statistics but recently, when trying to explain to a colleague, been troubled by my apparent lack of understanding of a very basic concept: the p-value ...
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1 vote
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### Question regarding post-hoc power analysis

I am having trouble with interpretation of a prospective superiority randomised controlled trial. Study characteristics: Study design: Alpha value = 0.05 1-beta = 0.8 Predicted effect size =0.15 [P1 =...
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### SIgnificant P-Value with overlapping boxplots

I'm confused about some of the results I got after plotting my data. I have a data set that includes tests scores and a binary group assignment of either polypharmacy or non-polypharmacy. the scores ...
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1 vote
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### Why are my P-Values for the scipy kstest on a uniform distribution so high?

I'm using the Scipy implementation of the Kolmogorov–Smirnov test to check whether collections of random values are likely to have been drawn from a uniform distribution. From what I understand, the ...
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### Verifying Holm correction line on FWER graph

I'm teaching a class about family-wise error rate, and have created a graph to illustrate how, when we increase the # of comparisons, the rate of type I errors increases rapidly (Family-Wise Error ...
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### Multinomial with small counts and many cells

I have data distributed as multinomial, with $N= 1,000$ observations divided among $n=10,000$ cells, with unequal probabilities $p_i$, for $i=1,...,n$. I would like to assess how likely it is that an ...
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