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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46 views

Is there any possible statistical test for this data?

I have a data set of the daily dosage of a drug that participants take against some signs and symptoms. The data are highly skewed to the left because there are a lot of patients with 0mg per day of ...
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constant sum question results analysis - please help

I ran a study with a constant sum question: participants had to divide 100 units (I called the units USD) between 5 possibilities. In other words, they had to bet on five possibilities: 1 object out ...
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T-Test comparing treatments

What Type of T-Test I can use on the following Problem: I have 3 experiments ( effect of treatment on the number of bacteria in food) where each experiment is replicated 3 times on different sample ...
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How to test for difference between table of weighted proportions

I'm wondering how one would go about determining whether there was a significant difference between the column/row values of a table of proportions. For example, given the following table: ...
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Screening for outliers / testing for normality - overall or within groups?

As I understand it, it depends on the test to be used whether the screening for outliers and the test for normality is performed within individual groups or with the total sample. If groups are to be ...
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Testing mean of two groups with their mean, lower CI (2.5%), and upper CI (97.5%)

I ran two MCMC simulations and want to compare whether the resulted mean of the two posterior groups are different or not. If I only have their mean, lower, and upper credible intervals, is there a ...
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t-test to compare weighted means

I have an unbalanced panel of paired differences. That is, my panel consists of 100 firm time series of paired differences with varying length. I have tested wether the unweighted mean is different ...
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Using Welch's t-test for samples of very different sizes

If I have two groups, one with a sample size of, say, 700,000 observations and another with 10,000 observations and I want to test the difference between the means of the two groups, what would be the ...
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1answer
33 views

Causal inference method for analyzing randomized control trial with covariates / pre intervention observations

I've got a seemingly easy situation, which turns out to be a little more complex than originally thought. Here's the Setup: We have a randomized controlled trial. Test and Control groups are the same ...
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Correction when comparing ratings with different inter-rater reliability

I had a survey where people rated two groups of things with a number and I found that the ratings between the two groups are not significantly different (using a t-test). However, I found that the ...
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What test for verifying statistical significance for difference in 2 groups [closed]

How to verify the difference in estimated effects of 2 variables on a dependent variable using a statistical test. Q: Determine the estimated effect of X1 on retention, controlling for a,b,c, Include ...
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Choosing a statistical test for three trials with continuous outcome

I have some data that represents three trials where cell populations were divided into two evenly sized groups. One group received no treatment while the other group received treatments (the ...
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1answer
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Paired vs Unpaired t-Test basics

Hope this is not too basic: I understand we used paired testing in situations where, e.g., the same subject is tracked before- and after- an experiment/treatment, e.g., before- and after patient ...
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R t-test comparing two proportions

I have two populations population 1: n=160, male=14, female=146 population 2: n=150, male=16, female=134 How can I test if the two populations are significantly different? I guess I have to use a t-...
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Detect if gaming strategy is better

I collect data about a videogame (think about an ego shooter with kills / deaths etc) Obviously the higher "kills" is and the lower "deaths" is, the better the players result is. ...
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Statistical comparison of coefficients over multiple models

I have question about statistical significance testing effect accros multiple model. Usually, with panel data we observe multiple cross-section units and account for each individuals fixed effects. ...
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One Sample Wilcoxon signed-rank with a negative effect size

Hi i got a Wilcoxon signed-rank done for a one sample t-test because the data failed normality tests. Whilst the result is still significant, the effect size is -0.364. Apparantely it uses the '...
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1answer
16 views

Choose proper test for two numerical vectors in different length

I am currently struggling to find the most proper test to serve my needs. The thing is, I have one data matrix. The columns are computational features and each row corresponds to a patient. The last ...
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Difference between Welch Two Sample t-test and Two Sample t-test

I would like to compare two means I have the following variables group variable (IND) 12 (161 observations) 17 (151 observations) output variable (pv1) scale from 1 to 5 I am working with R one ...
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3answers
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Compare two products directly or separately in a survey for t-tests?

I'm composing a survey where I compare two mobile apps and am not sure how to formulate the questions. Should I compare the apps directly like this: "Which app was more intuitive to use?" 1 (...
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R t-test table for a word document [closed]

I would like to compare the job satisfaction of part-time workers in the health industry and the financial industry. Should I do a t-test? How can I do this with R. Can I use stargazer to get a table ...
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1answer
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What to do if the data collection company accidentally gathered more data than we need?

This is actually a true story. While planing a study, my work colleague did a power analysis for an intended effect size and a priori power of 80%. It turned out that the required sample size was one ...
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Cointegration testing; order of the pantula principle?

In my times series course we learnt about using the Johansen Procedure to determine, if there are cointegrating relationships within a VAR model. My teacher gave us a function to implement it in R. ...
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1answer
52 views

Testing for normality with small sample sizes in order to use t-test [duplicate]

I run into a conundrum when determining whether a small sample is appropriate for a t-test. I know that if I meet the assumptions, a t-test produces approximately correct inference with any sample ...
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1answer
39 views

Representativeness test: how?

A survey to a representative sample of the population has been submitted. This sample is composed by 4.400 individuals. However, only 2003 individuals have completed to survey. I want to verify if ...
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1answer
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How can I compare two zero inflated continuous datasets?

I have two zero-inflated datasets such as, dt1= 0, 0.1, 0.125, 0, 0, 1.25... dt2= 1.01, 0, 0, 0.25, 0,... I want to check the differences, like t.test for ...
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Comparing job satisfaction of part-time workers from two different industries

I would like to compare the job satisfaction of part-time workers in the health industry and the financial industry. Should I do a t-test? How can I do this with R. Can I use stargazer to get a table ...
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1answer
22 views

two-sample two-tailed t-test in R using sample statistics rather than raw data

The second most popular answer to this question does not produce p-values that decrease as the stat being estimated gets further from the sample mean in the positive direction, only the negative ...
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Designing a stats experiment on Life Time Value (LTV) of the customers of a subscription product

I work for a subscription product that has two different channels in which customers can subscribe. Let's call them channel A (website) and channel B (mobile application). I have a hypothesis that ...
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1answer
34 views

extremely low p value when running t-tests

I am running some t-tests for unequal variances, unfortunately I cannot add the data here as it contains sensitive information. upon running a those tests, I got a p value of 1x10^-14. while the ...
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1answer
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Data analysis: 2 groups but all ratings from the same (two) individual(s)

If there are two groups (IV: treatment / no treatment) with say 15 participants each, and for each participant the same observer has completed a questionnaire (DV: outcome measure, completed once for ...
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Tips for the proper statistical method for analysing 104 Datasets in RStudio

for my last major homework before my masters in musicology I am trying to do a characterization of loudspeakers through psychoacoustic parameters. Though I am very interested in statistics I am either ...
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1answer
37 views

Should multiple testing correct with bonferroni ever reduce a p value's size?

I just did a series of 40 t-tests and then proceeded to use bonferroni correction for multiple testing and my P values reduced in size. Why does this happen? I was my impression that multiple tests ...
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2answers
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How would you test for a difference in mean group differences between scenarios?

Suppose I'm looking at gender differences across two scenarios (all respondents answered both scenarios) and I want to know whether the gap between men and women varies between scenarios. Suppose the &...
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2answers
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Compare regression coefficients within the same model

I ran a regression model with around 10 regression coefficients. I now want to test wether these regression coefficients are significantly different from one another. How do I do this? Is a Wald test ...
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91 views

Paired vs independent t-test for A/B test with underlying trends

There is a metric which has a natural cyclic pattern. We want to measure the effect on this metric through a A/B test. Examples: Metric is daily revenue of ice-cream trucks which is low during ...
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Statistical Significance In Sample Between Two Time Points

I have a set of time series data with one observation per week for each county in a certain state. I want to see if there is a statistical difference between the observations at the point in time ...
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FDR control on many t-tests performed on different sample size

I'm a PhD student working in bioinformatics, on genome sequencing data. My knowledge comes to its limits here on hypothesis testing and FDR-control/multiple-comparisons. Any help would be truly ...
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What is the mean difference between the two groups being examined? and How many degrees of freedom do the researchers have for this analysis?

I'm currently doing a bachelor's degree in English for Industries and doesn't have a knowledge in statistic but i need to take statistic for this semester. I have a difficulty to answer this problem: ...
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How to report post-hoc comparisons against 0?

In the following code, I fitted an anova model (aov$aov below) and tried to compare the marginal mean of each condition against 0 (using ...
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Finding alpha (level of significance) and beta

I am confused about the fact of how can we solve for the value of alpha (level of significance) when we are given acceptance region and sample size. E.g., If acceptance region is 48.5<sample_mean&...
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2answers
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Independent t-test on two variables

I'm working with Movielens and trying to find which of the two genders engage more by giving more ratings. Something like this: H0: On average every female user ...
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1answer
40 views

Using the null hypothesis to determine one or two tailed test?

This is a bit of a noob question so bear with me. Is it not true that the null hypothesis test determines the type of test (one tailed or two tailed) you would use. For example null hypothesis could ...
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Comparing n sample means

To preface, I'm a stat noob programmer, so sorry if this is a basic question. I have multiple (300+) exams that I had a variety of users take. The users could decide which exams to take. All the exams ...
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Independent samples T-Test on the sample animal population?

I'm comparing faecal glucocorticoid measurements (FGM) from a sample population of 7 (animals). Most samples were collected between 7am and 9am but some were collected after 9am and up to as late as ...
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t test vs goodness of fit test

Suppose I have two groups of data. I want to know if their distributions and / or means are different or not. Is it appropriate to do a two-sample t-test? Or should I go for a 2 sample goodness of ...
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t-test as a randomisation test [closed]

Can I do a randomization test using a simple t-test? In particular, I have data and already checked the difference in group means of dependant variables by using t-test, but I also would like to check ...
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Significant T-test with small mean difference but large standard deviation

I have recently run some analyses to test whether those participants lost to follow up are significantly different from those who stayed in the study. N= 590 for those who stayed and N=258 for those ...
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1answer
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Paired t-test with à priori known variance for Model validation

We have a multiple linear regression model $y = f(x1, x2)$, which has been fitted with measurements of a designed experiment of the input variables $x1$ and $x2$. Based on the design, the complexity ...
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34 views

Where to find t statistic and degree of freedom in T test in Google Sheets?

I'm using Google sheets to find TTEST scores. Its outcome is a single value, namely, p value. But in addition to this p value I also need to report degree of freedom and a t statistic value: t(degress ...

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