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Questions tagged [statistical-test]

A statistical test provides a mechanism for making quantitative decisions about a process or processes.

Statistical Tests

A statistical test provides a mechanism for making quantitative decisions about a process or processes. The intent is to determine whether there is enough evidence to reject a conjecture or hypothesis about the process. The conjecture is called the null hypothesis. Not rejecting may be a good result if we want to continue to act as if we believe the null hypothesis is true. Or it may be a disappointing result, possibly indicating we may not yet have enough data to prove something by rejecting the null hypothesis.

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Statistical test with file uploaded by user

I am currently trying to develop an app that could realise statistical tests on any file uploaded by the user. The problem is that I often encounter problems trying to do the tests and many "error" messages appears. Here I cannot make the t-test…
User34539192
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Getting multiple error bars in bar graph (R)

I am trying to plot a bar graph in R with 4 independent variables - time(t1,t2), group(1,2,3,4,5), distance(far and near) and cue(valid and invalid) with RT as the dependent variable. For the same, I have used the following code ggplot(b, aes(x=cue,…
Christina
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Is a multinomial logistic regression the appropriate "test" for this situation?

I have two columns in my dataset. y is the dependent variable and is categorical with three levels (unordered levels A, B and C) and x is the numeric independent variable. The example below illustrates the situation, but my actual dataset is larger,…
Viswa V
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How to get rejection region given significance level using python

I want to create a function that does hypothesis testing. One of the parameter is alpha, given alpha I want to get rejection region (by lookin up z-score table) how can I do this using python? for example: if I input alpha=0.05 it should return…
haneulkim
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getting the same critical values in johansen test

So I am trying to make an algorithm that test for cointegration: import matplotlib.pyplot as plt import pandas as pd import pandas_datareader as web import datetime as dt from datetime import date import numpy as np import os from…
benito.cano
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choosing healthy control from a very large dataset

I would like to run a unpaired t-test. I have a very large dataset of 500,000 participants and only 21 participants have a disease. how can I choose my healthy control from this large dataset? any thoughts would help. I am using R for analysis
EA90
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Error - Chi-squared approximation may be incorrect

I'm trying to do chi-square test on the contingency table Satisfied More Or Less Not At All Sat Lower Class 299 787 1876 Working Class 4594 10935 7660 Middle Class 8913 …
Jayashree K
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sample size estimation in R

I am working on problems from the book "Quantifying the user experience" by Sauro. But couldn't figure out the right way to do it. Assume you’ve been using a single 100-point item as a post-task measure of ease-of-use in past usability tests. One…
tarun14110
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Computing a chi square statistic from scratch using numpy/pandas, matrix computations

I was just looking at https://en.wikipedia.org/wiki/Chi-squared_test and wanted to recreate the example "Example chi-squared test for categorical data". I feel that the approach I've taken might have room for improvement, so was wondering how that…
baxx
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Implementing pythonic statistical functions on spark dataframes

I have very large datasets in spark dataframes that are distributed across the nodes. I can do simple statistics like mean, stdev, skewness, kurtosis etc using the spark libraries pyspark.sql.functions . If I want to use advanced statistical tests…
thentangler
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Regarding chisq.test (x, p) function for goodness of fit, how does R tell the degree of freedom of chi-square?

If I test x against a Poisson hypothesis, then I use mean(x) as lambda to calculate p so df = k - 2; if against a Normal hypothesis, then I use mean(x) and var(x) to calculate p so df = k - 3. How can R return a chisq value without knowing the df…
limestreetlab
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Typeerror : Newey West for OLS in python

I'm trying to run OLS regression using Newey West t-statistics in python using statsmodels. My code is something like this: import pandas as pd import statsmodels.formula.api as smf df = pd.DataFrame({'a':[1,3,5,7,4,5,6,4,7,8,9], …
Dark Night
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how to remove group from table in r?

I have to run a t-test and need to remove the group of people that responded with "no answer" which generated a third, 99 group. I keep getting an error message saying the grouping factor needs to have exactly two groups. And I want to keep groups 1…
begoniath
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How to get P value in the accumulation density plot?

I have a dataframe whoese strucuture is like this: > str(mydata12) 'data.frame': 228459 obs. of 2 variables: $ intron_length: num 0.787 0.799 2.311 2.396 1.77 ... $ intron_type : Factor w/ 3 levels "All_intron","All_retained_intron",..: 1 1 1…
Kyle
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How can I find the c-ctatistic or AUROC using logistic regression in R?

I am running a logistic regression to see how these factors/variables affect an outcome (Neurological Complication). How can I obtain the c-statistic -- also known as the area under the Receiver Operating Characteristic (AUROC) Curve? …
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