All Questions
Tagged with hypothesis-testing t-test
1,002 questions
0
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2
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53
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Suitable statistical test
I have 2 groups - people that were ever active on my website and people who were never active. Activity is a metric based on some actions - both groups of people visited the website.
Each group used a ...
0
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0
answers
29
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Why is a pooled mean necessary in bootstrapping the difference in means?
Formulated Question
In a two-sample bootstrap procedure for testing the difference in means, why is it insufficient to subtract the group-specific mean from each bootstrapped observation (centering ...
- 369
1
vote
1
answer
57
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What level of statistical significance to choose for test of equaility of seemingly unrelated regression coefficients?
It is possible to compare effects from models estimated as seemingly unrelated [1] [2] [3]. DVs may be related, IVs may be related, or both may be true. In any event, analysts test for equality of ...
- 326
1
vote
1
answer
37
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Is a binomial of Chi-Square or t test the correct test to compare dichotomous variables?
You have an ML model that outputs 100,000 out of a million observations of a dichotomous variable 0 or 1. You want to see whether the distribution of the outputted 100,000 observations of the model is ...
- 21
0
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0
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31
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How do I do significance testing in this experiment?
We have an internal search engine system similar to google. On a default config A, if we give a query, it will give 1000 results with a rank. If the same query was given again, it will again give 1000 ...
7
votes
1
answer
271
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Paired t test and CLT: What is supposed to be normally distributed?
I often read that the assumption of a paired t test is "that the data is normally distributed". And that the CLT will rescue you, if that is not the case when your sample size is large ...
- 911
0
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0
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25
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why can a t test not be used if a single data set is available as a null hypothesis? [duplicate]
I have a data set in which I want to compare whether there is a change. However, my null hypothesis is based on only one data point. But why can't I get this one data point to be recognised as the ...
- 185
1
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1
answer
114
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How to verbalise t test results
I'm reading up on statistics and yesterday I asked the question why the two different t tests give different results.
statmerkur gave the following answer
There is no contradiction. The rejection ...
- 185
7
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3
answers
568
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I have two different statements for the t test and the single tail test
I want to check whether the values of a group (ct2 are greater than the values of ct1). To do this, I have applied a T test which has the following results.
...
- 185
1
vote
1
answer
28
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How to Calculate the Confidence Interval of the Sampling Mean with Scale Sensitivity and Varying Sample Sizes?
I am currently facing a statistical challenge while comparing the average weights of two populations of larvae, and I need help figuring out how to perform the analysis correctly given the constraints ...
0
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0
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21
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statistical test for paired data with different treatments (ANCOVA? ANOVA? paired difference t-test?)
I have data like this (the data is made up):
...
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0
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0
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18
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testing coefficients in multiple linear regression
I apologise if question is trivial, but I could not find the solution. Assume, we are dealing with a multiple linear regression with iid Normal noise. In the book Testing Statistical Hypotheses by ...
- 668
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0
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39
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Test between model output over a binary variable
I have a set of features that includes a binary variable (called $B$) and some others ( binary or numerical variables, let's these covariates $X$).
I have a target variable that can be either binary ...
3
votes
1
answer
40
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Statistical test on proxy variables
let's say I am interested in performing a statistical test to determine whether the mean of two distributions, a and b, differ. But I cannot sample a and b. Instead, I can sample c and d, which are ...
- 165
1
vote
1
answer
54
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Two way anova or paired t-tests
i am looking to see if there is a difference in dissolved oxygen levels between pool surface (S) and bottom (B) samples at four sites (an up and downstream site in two creeks). There are 3 replicate ...
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29
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6
answers
5k
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Since we now have unlimited computation power (relative to historical norms), do we need to use statistical methods instead of simulations?
Allen Downey wrote a blog post in 2016 titled "There is still only one test" which discusses the advantages of running simulations over traditional statistical tests. It argues that since ...
- 483
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0
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23
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Testing whether mean sample difference between two groups is different in two different samples
Suppose in a medical study there are the following students recruited to the study:
300 Japanese males, 500 Japanese females
600 Australian males, 700 Australian females
The particular study is about ...
2
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1
answer
45
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The F-test and the t-test reject the null hypothesis while the KS test and the Chi-Squared test do not
This is a follow-up question to How can the F-test reject the null hypothesis while the KS test does not?.
Let's consider I perform the following tests:
Two-sample Kolmogorov-Smirnov test (KS-test),
...
- 444
2
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0
answers
33
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Problem regarding False discovery rate correction for multiple comparison
I am conducting research to find association of a gene with a disease. It's a case-control study. I have divided the cases into groups A and B based on genotype and controls into groups C and D. I ...
4
votes
2
answers
365
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confidence interval and rejection
Assume I have a data sample $X_{1}, \dots X_{n}$ from a normal distribution. Then, we consider the following hypothesis
$$
H_0: \quad \mu = \mu_{0}
$$
and alternative
$$
H_1: \quad \mu \neq \mu_{0}
$$
...
- 668
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0
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41
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Confusion regarding t statistics, or any hypothesis testing in this case
So I found an interesting example in one of the great books in statistics : "The Practice of Statistics for Business and Economics, by David S Moore". It has the following T-test examples.
...
8
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6
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733
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Is it better to perform multiple paired t-test or One-Way ANOVA test
I have 7 patients with blood measurements from two different tissues and at two different oxygenation states. We first took measurements from tissue A and B (Normoxia) and then we administrated oxygen ...
- 201
0
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0
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58
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Testing difference between regression coefficients for different greoups
I am aware that this questions was addressed several times in this site and that there are certain papers discussing this issue for instance 1, 2.
USING THE CORRECT STATISTICAL TEST FOR THE EQUALITY ...
- 431
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0
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39
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Comparing sample means to standard measurements
I am trying to best address how to determine if a sample measurement is statistically different than a standard.
If I measure any variable (lets say mass) for a sample 1000 times to determine an ...
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0
votes
1
answer
99
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Paired or independent sample T-test
I have a statistical project that am working on that is made up of two groups(control and intervention) and the participants in the two groups are different from each other. Measurement of biomarkers ...
- 3
3
votes
1
answer
175
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Paired t-test of two algorithms
I want to compare the speed of two algorithms. However I'm having troubles interpreting the results. Is my approach correct?
Null hypothesis: The algorithms have same speed
Alternative hypothesis: ...
- 143
0
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0
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37
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Is it possible to conduct an F test without fitting a restricted model?
Say I'm fitting the following regression:
$$
Y = \beta_0 + \beta_1X_1 + \beta_2X_2 + \beta_3X_3 + \beta_4X_4
$$
If I was interested in testing the hypothesis that $\beta_2 = 0$, I know I can do things:...
- 21
2
votes
1
answer
19
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selecting the most appropriate statistical test for comparison of multiple independent variables belonging to two groups
I want to compare the drinking water chemistry of two areas. A disease is prevalent in one area while the other area is almost free from this disease. I have measured the concentrations of 10 ...
3
votes
2
answers
146
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Replicate t or F test from regression using regression likelihoods
I've heard that the t-test and F-test we use to get the significance of our regression results are derived from the likelihood ratio test, but I'm having trouble replicating the p-value of the t/F ...
- 425
0
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1
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44
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Test for significant difference between two groups measured across time
I have two groups of time-dependent samples whose measured value changes nonlinearly with time. There are 3 samples in group A and 3 samples in group B. An example of my data is illustrated below.
...
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2
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3
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246
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Hypothesis Testing for Means & Proportions. t-test vs z-test
How can I convince my teacher that he is wrong in this task? We were given the following task and my teacher says I have to use a z-test. In my opinion I have to use a t-test.The task is as follows:
A ...
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3
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1
answer
109
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Two-Group Hypothesis Testing
Will unpaired t-test, definitely reject the null hypothesis if there is a non-zero difference in the population means for the two populations from which the samples are taken?
- 681
5
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2
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618
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How does reducing my alpha-threshold to 0.005 affect my required sample size?
Among statisticians there is an ongoing debate whether the long-standing "standard" threshold for declaring the outcome of a statistical test as "significant" (a.k.a. alpha-level) ...
- 356
1
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0
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24
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Paired, Two Sample or Repeated Measures Test
I'm trying to understand when to use a paired T-Test over a two sample T-Test. In most cases it's clear but I have the following hypothetical scenario.
A social media company claim offer a feature to ...
- 11
0
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0
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15
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Unpaired comparison of groups with unknown but equal sizes and unequal variances
I have computed confidence intervals for the R-squared performance of different PGS models (via r2redux, as described in this paper) and now I wish to conduct statistical significance tests of their ...
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3
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1
answer
118
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Repeated measures ANOVA for case-control study
I'm working with two groups - patients and controls - and we've collected data on 36 continuous measures (biological indexes) for each individual at 4 different time points. My primary focus is on ...
- 381
0
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0
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68
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One-Way ANOVA for two groups VS. t test
When comparing 2 groups (K=2), we can either perform a t-test or f-test of One-Way ANOVA, because the f-test is equal the t-test squared(t^2 = f), it essentially goves the same resilt, right ?
Only ...
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2
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1
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129
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How can I calculate the minimum required sample size for a one-tailed paired t-test, testing whether the difference is greater than 5?
This Cross Validated answer states that it's valid to do a paired t-test to test whether the difference is greater than a certain value (e.g. 5) by changing the specified value of 𝜇 in the null/...
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0
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1
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65
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Distribution for which one-sample t-test yields inflated type 1 error rates
Type 1 error rates of the one-sample t-test (two-tailed) can be inflated for example for data from the exponential distribution.
However, I am looking for distributions which yield inflated type 1 ...
- 1
6
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2
answers
361
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Using a t-test to test effect size
In my line of work, I work with large data and often run stat tests to compare differences between groups. The problem I am facing is that if I use a $t$-test to measure any difference, the result ...
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4
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1
answer
282
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Standard deviation squared is variance. What is standard error of the mean squared? [closed]
Is it correct to say that there is a sample variance and a mean variance, and their square roots are the standard deviation and the standard error of the mean, respectively?
0
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1
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44
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Inferrring correlation between two variables from two similar samples
I have a dataset that has both bad and good data. A sample of these two datasets are as below:
Bad
ID
badness
protection%
100
50
5
200
30
100
300
60
20
Good
ID
badness
protection%
101
0
0
201
...
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5
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1k
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Compare 90th percentiles of two samples (confidence interval, test)
I have a dataset of ambulance response times before and after a quality improvement change. I'm looking to see if there is a difference in response times before and after the change. Specifically, I'm ...
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3
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2
answers
502
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How to use one-sample t-test on skewed distributions?
I have been reading that people use the one-sample t-test also for skewed underlying distributions, saying that for a high enough number of datapoints (I read for example N=30 and N=100 in some places)...
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2
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0
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79
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How to evaluate model's performance using a K-S test
I am wondering if a K-S test or other test can be used for comparing models' performance. For example, I have two prediction models, the prediction result of first model is ...
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6
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1
answer
100
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Which family-wise correction is needed for one-sided t-tests in a randomized controlled trial with several independent measures across groups?
I conducted a randomized controlled experiment with groups $A$, $B$, $C$, and $D$, each containing around $40$ human participants who saw one of four variants of a website. Group $A$ saw a baseline, ...
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1
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1
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83
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If you change the sign of a two tailed test does the p value remain the same?
If the results of a t test are reversed are the p values the same?
I am running an experiment:
Treatment: sample size - 5k and metric value - 0.57 Control: sample size - 5k and metric value - 0.62
The ...
- 65
0
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1
answer
40
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If two interventions, A and B are both effective i.e p-value is significant, is there a way to know whether A is MORE effective than B or vice versa?
Im new here and also consider me as a total beginner in statistics.
So in my scenario, lets say there's two learning interventions, Intervention A and B. The participants are divided into two groups, ...
1
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0
answers
43
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How to compare two groups for the same construct, measured by two different questionnaires within each group?
I’d like to compare two randomized (independent) patient groups regarding quality of life.
The challenge is that each of these two groups comprises patients having two clinical diagnoses. For each ...
- 121
0
votes
1
answer
65
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Hypothesis test on binary preference [duplicate]
I have two product designs and I want to see if there is a significant difference between which people like which design the best. I did a survey where I showed a photo of each design and asked ...
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