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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How to compare two groups of discrete states?

The dataset includes 25 patients in one group (low intensity of a certain parameter) and 27 people in another group (high intensity of the same parameter). One or more teeth were treated for each ...
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Is the intercept term in a simple linear regression a nuisance parameter when we want to test whether the slope is different from zero?

Assume that I cannot use least-squares estimator, so I don't have the intercept and the slope and only know one parameter at a time. Is the intercept term in a simple linear regression a nuisance ...
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Technical efficiency measurement using Tobit model

I want to measure the technical efficiency of layer poultry farmers producers using the Tobit model. but I collected the data and enter the excel sheet to import it into STATA 13. Now I am confusing ...
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Which statistical test should I use to compare two models (multiple runs) on the same (big) dataset?

I want to compare the performance of two stocastic models on the same datasets (>10k samples). To this end, I run 5 runs for each model (different seed) and I can compute the mean and std for each ...
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Are there restrictions on the use of modified Thompson Tau?

I've been running an experiment in which I apply Modified Thompson-Tau to samples drawn from a standard normal distribution, the goal being to understand how $\alpha$ and the sample size [draw_size in ...
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Hypothesis testing of two dependent samples when pair information is not given

For two samples equal sample size $(n\ =\ 100)$ that are randomly selected and dependent, only the sample means$(\overline x_1, \overline x_2)$ and sample standard deviations($ s_1,s_2 $) for both ...
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Justification for conducting independent samples t test on non normal data

I've conducted a study comparing two different teaching strategies in two different sections of the same class; I gave participants in both classes the same 5 tests and wanted to see if test grades in ...
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Need equality of variance test between control and experimental conditions on a within subjects with replication dataset

I have some proteomics data of 16 biological replicate samples split between 8 control and 8 knockdown. One of the tests I wanted to do was to see if the knockdown impacts the variance of the protein ...
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One sample t-test equivalent for repeated measures design

I might be looking for something fairly obvious but here is my setup: I have one group of participants who will perform multiple (different) tasks in an experiment. For each one of the tasks, I want ...
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Statistic tests in "table 1" - which to choose?

I have made a table overall comparing two cohorts - a "table 1". The table includes gender, age and 2 different scores from the two cohorts. I would like to test if gender, age and the 2 ...
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Improving A/B test with additional variable (time spent)

I have a typical example of A/B testing where we want to investigate the change in user behaviour after having tested a new website design on a specific group of users. The metric that we're using (...
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Do I need to apply Bonferroni Correction?

In my study I wish to perform three paired t-tests. The study compared times recorded to complete a test from before and after an intervention. The test is split into two parts (A and B) and the time ...
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Reporting the results of a continuous moderating variable on a categorical independent variable

I'm working with a dataset that was collected to test the following [adapted] research question: Does listening to music (categorical x; 2 conditions: pre_music - post_music) affect test scores (y; ...
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How can I choose between homoscedastic and heteroscedastic

I want to calculate the p-value between subgroups of my samples. For that, I am using the T.TEST function of Excel. But I do not understand the last parameter, type: Paired Two-sample equal variance (...
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Hochberg/Bonferonni correction for multiple one-sample t test

I am trying to conduct a content validity analysis where I want to test if a certain item (e.g. a question) can be related to a certain construct (e.g. depression). I've let people fill in a ...
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Assuming normal distribution for service time (queuing theory)

I was waiting in a long line a few days ago and "for fun" I tried to create a confidence interval re:when will it be my turn. For that I looked at the # of people before me, and how long it ...
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How to compute the t-statistic for only one cumulative abnormal return (event study)?

I am computing the t-statistic for different values of cumulative abnormal returns $CAR_{T}$ during the event period, for (T=-5,....,0,...,5) . The formula I use is the following: $t_{T}=\frac{CAR_{T}...
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Three versions of the independent two sample t-test (and R)

This post concerns three versions of the independent two sample t-test: Student's t-test uses a pooled standard deviation in the denominator (all equations are shamelessly copied from Wikipedia - ...
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t-test equal variances, unequal small sample size, not normal

I have two independent groups. Group 1 with 16 samples and group 2 with 10 samples. I want to know if the means are statistically different so I was thinking of a t-test for 2 means for equal ...
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What kind of test to perform for this data?

This is example data, but structured similar to my data. Say, I want to perform a test of gender difference in height. Let's say I am doing a test of height (cm) across gender, with random samples ...
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Do post-hoc tests need to be corrected for comparisons at different time points?

My question is a follow-up to this question, Statistical test for paired data at multiple time points?, where the OP asked about comparing paired data (left and right measurements) taken at three ...
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To carry out a T test for two tests of data from one patient using the same metric do I have to assume the differences is normally distributed?

My supervisor told me that to carry out a t-test on two different models to see which one is statistically better I needed to carry out a normality test (or just find if the data is normally ...
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Spearman's Rank Correlation Tests and Independent Sample t-test

If I would like to select which variables should I include in the logistic regression model, should I do a correlation test first or a t-test? Also, for Spearman's Rank Correlation Test, do I need to ...
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Statistical significance of difference between two time series

There are two groups of samples. The number of events on n-th day is measured for each sample. The average is measured for each day for each group of samples Days after first event average events ...
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running multiple t-tests across large dataset

I'm trying to work out if a t-test is the most appropriate in this situation: I have a data frame which looks like the one below but my data frame has aprox 37,000 rows. I'd like to run a t-test on ...
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Can I use a One-Sample T-Test to compare Employee Turnover for a period against an industry Benchmark?

I have collected employee turnover rates over the year. The attrition rates are as such: Month Attrition Rate Jan 2.23% Feb 1.40% Mar 2.99% Apr 1.43% May 1.72% Jun 1.15% Jul 1.64% Aug 1.60% ...
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comparison of a sample to another sample described by a histogram

I want to compare two groups -- a population and my sample. I need to find out if the sample is a representative sample of the population. Normally, I would use the Welch t-test to find out if the ...
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Should I normalize returns when performing a paired t test?

I am trying to see what trading strategy is better with back testing. The data is The daily FX rates from the last 20 years. However, each of the 2 strategies generates different entry/exit signals, ...
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Conditionally efficient statistics and manipulating power of a test

I am struggling with a problem where I need to report when the mean of a time series has changed (regime change). I also need to deal with small samples. The benchmark is a basic t-test. I am aware of ...
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Conducting multiple weighted t.tests to count over what fraction of a population a model performs significantly better or worse than another

I have two different model families $A_i$ and $B_i$ each of which predicts a continuous value for an item $i$ at various points in time throughout a given day. For a given day, and item $i$, I can ...
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The right statistical test when you have a before/after + trial and control group

I am trying to understand what statistical test is best in circumstances where you have both a before/after (so paired data) and a control group There are t-tests available for one of each scenario (...
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Hypothesis testing for increase in sales

A company is planning to setup the option for self checkout (SCO) in all of its stores. As a trial, they are looking to estimate the benefits of SCO in terms of increase in transaction volume by ...
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Independent Samples T-test vs Paired Samples T-test for hypothesis testing (machine learning algorithms comparison)

The scenario is as follows: I have 1 dataset and I want to compare the performance of different algorithms. Let's say A, B, C. I train each algorithm a 1000 times in one training loop. At the ...
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How to check if improvement in search results is significant

I'm implementing a search engine in two different ways A and B, and I am comparing their accuracies. Accuracy of system A is measured as follows: Given a query, I check if system A gives me the result ...
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Stat sig results on underpowered experiment [closed]

I ran an experiment that was powered enough to detect lifts of 1% on my 2-sample test. Make it really simple: I have two normal distributions and want to compare the means, so I ran a 2-sample t-test ...
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Outlier detection using VAE and multivariate T-test

I've seen this answer Outlier Detection Using VAE Latent Space about this question, however I'm not fully satisfied with the answer. Context: We have a fully trained VAE which maps $R^N$ into a $R^M$ ...
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Special scenario when the same participant acts as both the control group and the experimental group scenario, but at the same time

I would really appreciate any advice here on if there are any special parameters I need to use for this example. I am looking at the effect of an analgesic on pain level after ocular surgery. Both ...
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CLT for t-test with unequal sample size; one group < 30?

CrossValidated has many discussions on how unequal variances are not a practical issue for two-sample t-tests when Welch correction is used and on how normality assumptions do not play a role (in Type-...
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Statistical test for low treatment sample size, high nb of record and large control group

I am looking to analyse the efficiency of a treatment. The problem is that I have only 3 patients in the treatment group. However: I have thousand of measurement of the value of interest for these 3 ...
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Approximate distribution of test statistic for weighted sample mean

Let $$ R_{i}(t) \sim \mathcal{N}(\mu_i, \sigma_i^2), $$ denote the one period return distribution for asset $i$, from which we observe the iid samples $\{R_i(t)\}_{t=1}^{n_i}$. The MLE sample mean and ...
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How many parameters in my mixed effect model (for t-tests)

I have the following mixed effect model; penicillin_model = lmer(yield ~ treat + (1 | blend), data = penicillin) Treat contains 4 categories ...
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Different Number of Judges Scoring and how to Rank

I have looked everywhere and I am struggling to find a solution. Granted, I am no statistician but I do have some knowledge of basic statistics. Any help is truly appreciated! There are a number of ...
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Why does the one-sided T-test reject the Null Hypothesis while the two-sided doesn't?

I'm not that familiar with statistics, especially not with T-tests, however I need to apply a T-test for my ...
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Interpreting coeftest results; z-test; t-test, unfamiliar with the output

I am using coeftest to run z- and t- tests on a few different pieces of data. The output comes in this form: fit <- lm(dest_flood ~ type_flag, data = runsample) coeftest(fit) ...
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What statistical test should I use (biostatistics)

I am comparing sperm motility between 2 sets of samples (2 groups). Motility just means weather the sperm are alive or not, in this test I am just looking at that. If its moving, then its alive (I ...
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Testing accuracy of black-scholes model

What is the best way to assess the accuracy of the prices given by a Black-Scholes model? Taking into account that, for example, the model could be used to price binary options, and a binary option is ...
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Comparison of total counts vs. comparison of mean counts per participant in exploratory data analysis

I already came across this question: Difference in means vs difference in proportions, but could not answer my question based on the answers and comments there. My question would be this: Suppose ...
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what statistical test should be used for testing number/proportion of people who agreed in 2 different years

I want to measure if the number of people who agreed on a likert scale (1 strongly disagree - 5 strongly agree), so responded with a 4 or 5 had a statistically significant increase from the previous ...
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1 vote
1 answer
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Is it possible to compare means of pre & post intervention questionnaire for only 3 participants?

I am completing my dissertation which was to determine if a 6-week expressive writing intervention would reduce aggressive behaviors & increase emotion regulation in students. My first variable (...
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Convergence Rate of $t$ Test Statistic (Regression)

Consider a simple regression model, $y=\beta^Tx+\epsilon$, say using the cars dataset. We get the following summary: ...
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