Questions tagged [t-test]

A test for comparing the means of two samples, or the mean of one sample (or even parameter estimates) with a specified value; also known as the "Student t-test" after the pseudonym of its inventor.

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Sample size for mean comparison

Suppose that I have a new machine so I want to compare it to the older one. I would like to conduct a mean comparison of a parameter, to verify if these 2 machines produce the same results or not. How ...
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t-Test for testing non-zero Multiple linear regression coefficient

I am supposed to use a t-Test to test wether a regression-coefficient is zero or not, atleast it is what i understood from it(see down below for the literal translation). The scenario is, that i have ...
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Two sample t-test for groups in same distribution

I am trying to evaluate which test is appropriate for detecting whether the learning curve of somebody doing a specific kind of surgery will influences the time of how long it takes to conduct the ...
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Statistical test for determining difference from true measurement?

So hypothetical situation is as follows: Let's say I make a neural net that can determine the length of an object in an image in centimeters. I also have an actual length for that object. My goal: ...
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Reaction time not normally distributed

I am trying to analyze a dataset. My independent variable (IV) is instructing participants to think fast or slow and my dependent variable (DV) is participants' average reaction time. As expected, the ...
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Reaction time not normally distributed in R [duplicate]

I am trying to analyse a dataset. My IV is instructing participants to think fast or slow and DV is average reaction time. As expected, the averageRT is not normally distributed. I'm trying to run a t-...
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Appropriate test for effect of learning curve(number of years) on dependent variable

I am trying to evaluate which test is appropriate for detecting whether the learning curve of somebody doing a specific kind of surgery will influences the time of long it takes to conduct the surgery....
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Propotion test vs T-test

Proportion test - Helps to identify if there is significant difference in proportion across the samples.(i.e. the values are in proportion and denominator is in sample size of entire proportion) ...
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The difference between two population means

I am trying to answer this question: ...
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What's the Statistical test to use to compare the means of two correlated time series (i.e., t-test for time series)?

I hope everyone is doing well. I have a question about the statistical methods of comparing two time series. I got monthly data from 1/1/2019 – 1/10/19 (10 observations). I would like to compare it to ...
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Confidence interval for difference between regression lines

Assume two linear regression models $$ Y_{b} = \beta_{0b} + x\beta_{1b} + \varepsilon_b \qquad \text{with} \qquad \varepsilon_b \sim N(0, \sigma_b^2) \\ Y_{r} = \beta_{0r} + x\beta_{1r} + \...
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Hypothesis testing for count variables in (possibly) nested data

I am analyzing word usage in multiple two-person conversations between students and teachers, and want to test whether the usage of a given word differs between the two speaker roles. My interactions ...
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How do you calculate and report the expected value range for a one sided t-test?

How do you calculate and report the expected value range for a one sided t-test? Here is an example: The claim is that the average weight of chickens on a farm is at least 5 pounds. A random sample of ...
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Do I accept or reject the null hypothesis using the t test and critical value based on my results here? [closed]

I am trying to prove that there is a significant difference in plant height of two sets of data (one from soil-based system and one from hydroponic system). I have calculated the SD for both sets of ...
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Do I need to use a significance test?

I have just started studying statistics needed for data science. I am using the " Statistical Methods for Machine Learning" book by Jason Brownlee and Statquest videos as reference . I tried ...
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What should we do when t-test is not applicable?

To know if a med is effective or not we use a t-test; the independent variable is binary (placebo or not) and the dependent one is continuous (a measured value). What if the features are flipped (the ...
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Calculating the difference of two independent sample means. P-value is < 0.05, but the standard error of the mean overlaps 0?

I have a list of values (test) and another list of values (control). If I use python to calculate the p-value between a test and control variable: p_val = stats.ttest_ind(test, control, equal_var = ...
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Calculate p-value for one-sample T-test in SPSS: 1 - p/2?

In SPPS, for the p-value in a one-sample T-test, 1-tailed: When you find a mean that is in the opposite direction of your alternative hypothesis, do you have to do 1-p/2 or just p/2? Thank you!
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one sample t-test ${\rm H_0}:\mu=1$ vs ${\rm H_0}:\mu<1$

Suppose I want to test \begin{align} &{\rm H_0}: \mu = 1,\notag\\ &{\rm H_A}: \mu < 1, \end{align} and I get a p-value of 0.3, meaning I don't reject the null for the alternative. In this ...
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Alternative methods to multiple paired t-tests?

For my project, I want to compare user experience between different assessment formats for 4 different diagnoses groups. I am only interested in the within-group differences and do not want to compare ...
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Multiple Linear Regression Dataset

Does anyone have any ideas of datasets which are suitable to fit a multiple linear regression model. However, I would like this specific dataset to have a binary variable which can be used for a two ...
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Using test hypothesis to prove I ran a sufficient number of simulations

I simulated a system using discrete-events simulation, more particularly next-event simulation. The system is M/M/1 (infinite FIFO waiting room). Whenever the system is jobless, the server shutdowns. ...
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Multiple within-group comparisons

For my project, I want to compare test anxiety on game-based and traditional assessments for four different diagnoses groups and only look at within-group differences, i.e. whether diagnosis group 1 ...
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Confused about Two Sample Proportion Tests - am I performing this correctly?

I am dealing with an advertising dataset that includes hundreds of advertisements, how many clicks each ad receives, whether the amount of clicks received is considered "high" or "low&...
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T-test and tree don't match logically

I would like some help in a machine learning homework. First I want to make clear that I don't think this is considered cheating as I am just asking for help in understanding a result, rather than ...
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Independent t test for two proportions

I am doing a study where I compare male to female participants in 4 different age groups (0-20, 21-40, 41-60 and 61-80). I want to check if there is a statistical difference in percentage between the ...
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1answer
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Right Side T-Test - Reject Null but Sample Confidence Interval Includes Hypothetical Value

This has me puzzled. I am doing a right sided t-test where the null hypothesis is rejected based on the critical t value and the p value but the sample confidence interval includes the expected value. ...
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t-test - subjects were measured for different times

I am hesitating between whether or not to report t-test results. I have a dataset where each subject was under two treatments; within each treatment, the subject was measured X times. One thing to ...
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1answer
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Which t-test it the right one for my data?

I have the data set below. Two Groups which were tested at 3 different timing. Between the tests, there were 5 weeks of training. I think, I should do the t-test for dependent variable. (I need ...
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Can't transform data into a normal distribution

We have data on the counts of a certain disease in our city. We're trying to see if there's a difference between the male and female instances of it. We have decided to t-test for this, but both of ...
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Would a T test be appropriate for determining the significance of an algorithm's results?

Say you have an algorithm which should yield a higher score when given two similar images and a lower value when given two images that do not resemble each other. Two sets of tests are run, one where ...
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T test for poisson distribution

I have a sample ($n = 10$) from a Poisson distribution. It was said that the t test with 9 degrees of freedom cannot be used to test $H_0: \lambda = 5$ against $H_1: \lambda \ne 5$. I know that a ...
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When to use t-test and Chi-squared test

I want to find correlation between win_lose and other columns starting from ID to eki_id. ...
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Ranking samples of a stochastic function

Suppose we have samples $f_1, f_2, ..., f_n$ of some stochastic function $f(\vec{x}): \mathbb{R}^n \rightarrow \mathbb{R}^1$ for different arguments $\vec{x_1}, \vec{x_2}, ..., \vec{x_n}$. We may ...
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t-test or z-test: assume normality or s≈σ?

Let's say I have a large sample ($n>30$) with mean $\bar{X}$ and standard deviation $S$. I can calculate only: $T=\frac{\bar{X}-\mu}{S/\sqrt{n}}$. If I want to use t-test for a hypothesis, then I ...
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Why do faux::rnorm_multi and faux::rnorm_pre produce different results in a simulation of a repeated measures design? [closed]

I want to simulate repeatedly drawing two dependent samples for a t-test (ultimately for power simulation). To generate the correlated samples, I tried two functions from the faux-package: rnorm_pre: ...
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How can I compare an expected value to log transformed data?

For a school project I need to show that the data I was given does not match the expected value found in literature. My data is the diametre of 150 particles and the distribution is pretty close to ...
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t-test raw vs date aggregated data

So I am a a bit confused here. My test is simple, I have a control population and a treatment population. The treatment population is shown an image before answering a yes/no question and the control ...
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1answer
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Which test to perform for significance testing when comparing accuracies from two models

I need to perform a test to show that accuracy results from different models are statistically significant (or not). I have been looking into https://www.socscistatistics.com/tests/ but I do not know ...
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what does For a significance threshold of 0.05, if the null hypothesis is true mean

Although it's a simple question and I know what the null hypothesis means, I couldn't understand this sentence. For a significance threshold of 0.05, if the null hypothesis is true, then the ...
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How to Test Significance of Trading Strategy? [closed]

I am wanting to try out a new trading strategy, and it has proven successful on a simulator for the past few days. I do want to collect some more data and see if my results are statistically ...
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T-test, Chi-squared test and hypothesis testing?

I am not an expert in the field of statistics and my questions might be stupid, please be indulgent :) I've come across many videos/articles about T-test that suggest sampling data when their dataset ...
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Performing Paired Sample t-test on sampled height measurements when using different platform sensors?

I’ll be upfront, my Achilles’ heel is understanding how to apply statistics. I want to test/compare the relative accuracy of sampled height points created at set intervals (say 50 metres) along a 1 ...
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Virtually everything is significant if the sample sizes are large enough

Forgive me, I'm sure this is a very simple statistics question. I frequently run into the problem where I try to determine the effect of a single variable, so I split my data into sets that are ...
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Wilcoxon signed rank test or t-test if data is highly skewed?

I have an variable that is highly skewed and I want to test whether my mean is equal to some fix value in another population. I only have the arithmetic mean of the other population. Because I prefer ...
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1answer
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t-test difference in size of each sample?

I have a daily process that's been going on for a few months. Now I'm trying to infer if a change to the process is significantly different. I let the new process run for two weeks because I can't ...
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1answer
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T-test or wilcoxon

we have 2 independent groups of datas and one of them has normal distribution and the other doesn't How can I compare the means of this groups ? Paired sample T-test or wilcoxon test?
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Comparing individual proportions

I am designing an experiment where each subject performs a selection of items in two different conditions, treatment and control. Among 20 items, they can choose as many as they want. Some of those ...
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3answers
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Paired t-test results

I'm running a paired t-test to compare before and after counts. Here's what my data looks like: before <- c(102,122,64,0) after <- c(38,39,23,16) Here's my ...
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Sig Tests for weighted means

I got the challenge to integrate a test of significance into a Tableau dashboard. The dashboard shows weighted means for metrics such as income, age, etc. for two groups that can be defined by ...

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