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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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1answer
232 views

Reproducing t-test in R gives different result than built-in function

I'm trying to reproduce how a t-test works using the example from page 211 in The Art Of Computer System Performance Analysis by Raj Jain. The calculation is as follows: ...
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0answers
10 views

Probability test for large and unequal sample sizes

I have two data sets (sentiment scores of two texts) for which the sample data in each set is shown below: Data set A = -2,-2,-2-1,-1,-1,-1,-1,-8, 0, 0,-12,-9 Data set B = -2,-2,-2,-2,-1,-1,-1,-1,-1,...
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0answers
16 views

nested data, one type of measurement, t-test?

I have data with the following variables: mutant | wild-type, treated | untreated, and one type of measurements (size) for time point 1 and 2. The data is roughly normal. My ultimate H1 is that there ...
1
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3answers
46 views

Paired categorical data--which test to use

I am trying to determine which statistical test to use for the following: I used a rubric to determine students' level of achievement on two different tasks (see table below). I want to know if their ...
2
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0answers
28 views

T-test for “discrete” variable

In my dataset, I have 2 columns. Both of them are a percentage. However, they only take the following values : (0,10,20,30,40,50,60,70,80,90,100). I would like to know if I could do a t-test on those ...
1
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1answer
40 views

Comparing two algorithms. Paired t-test, independent test or mixed effect linear regression

I have two algorithms running on 100 benchmark instances. I want to test if there are significant differences in their mean average error. A significant part of those two algorithms is not ...
1
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0answers
10 views

Correction for different number of sampling days with individual samples for paired t-test

I have pre and post-fire data from GPS collars. Unfortunately, not all animals were collared at the same time and none of the animals were collared any more than 25 days before the fire. For each ...
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2answers
54 views

Validity of t-test, Welch's t-test and Mann-Whitney U test

Suppose you wanted to compare whether the returns of stocks A and B had the same mean. It is unlikely they have the same variance. To do this you performed a t-test, Welch's t-test and Mann-Whitney U ...
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0answers
20 views

How to compare two variables that have first-order dependencies?

I have the following data, ...
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0answers
20 views

Alternative test to paired t-test? [duplicate]

I need to compare data from paired groups, but my distributions are non-normal, and my sample size is small. Are there any tests I could apply? I've been looking into non-parametric alternatives like ...
2
votes
0answers
31 views

Chi-square origin of the name

What are the origins of the names and letters in these distributions: What is the origin of the name in chi-square distribution $\chi_k^2$? And the origin of $t$ in student's $t$-test? And naming $...
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0answers
13 views

Intuition on Linear Discriminant Analysis and Z-Test/T-Test

I am trying to get into Linear Discriminant Analysis without getting too much into linear algebra and also having a lack of geometric fantasy. To obtain an intuition of whats going on, I just want to ...
1
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0answers
9 views

How would someone name a “kind of” post hoc power analysis using a priori mean difference estimates?

Imagine a researcher conducted an experiment and tested an hypothesis using a two independent samples approach. It was the first experiment of this kind, so the researcher had no idea about a possible ...
0
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0answers
10 views

How to calculate Standard Deviation in weighted Paired t-test?

I'm attempting to figure out the formula for a weighted & paired t-test. For reference, I want to know the weighted equivalent of R's...
0
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0answers
9 views

How to compare a binary choice test?

We have two separate algorithms, A and B, which, given some input, produce some result. Users are to be shown multiple examples where each algorithm was given the same input, and for each input, ...
0
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0answers
6 views

distribution test among different sample sizes

I want to test 2 data sets with different scales. Data set A is 10K record, with about 200 outliers, and data set B has around 1K record with 20 outliers. How can I test whether the two data sets have ...
0
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0answers
8 views

How to calculate the Shapiro Wilks with data that is constrained

When performing an ANOVA I have the residuals that I wish to show in a Normal Probability plot, and wish to calculate the Shapiro Wilks test. The number of observations is n, the df of the residuals ...
0
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0answers
22 views

Should I use dependent t-test or independent t-test

I have a software that produces a sentiment score between 0 and 1 given an input sentence. I want to test if this system produces biased scores based on the gender of the subject used in the sentence. ...
1
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0answers
20 views

12 samples, split into 2, 68 variables measured; 68 paired T-tests?

I collected blood samples from 12 patients. Each sample was split into two different storage vessel (24 total aliquots). All 24 aliquots were analyzed for 68 elements. Since the patients are selected ...
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0answers
38 views
+50

Simple main effects and separate t-tests

Lets say I have 2 factors and fully balanced groups: Between-subjects: condition (0, 1) Within-subjects: time (time1, time2) I ...
0
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1answer
20 views

T-test or Mann-Whitney U test [duplicate]

Given the central limit theorem, can you always use a t-test to test a difference between two groups even if the data are not normally distributed but the sample size is large enough? Stated in ...
0
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0answers
13 views

How to Calculate Sample Size for a two samples Welch's t test given a wanted power for an expeted effect size (without R)?

I have found no answer on web search engines for that. And even though I was able to find here some answers on how to calculate the power of a Welch's t-test here, they were expressed in R code. As I ...
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0answers
17 views

Omnibus 1-sample t-test?

Seems like this should be simple enough, but I haven't been able to find a solution, or even a discussion on the issue: What is the appropriate test and model to answer the question "Is group mean A, ...
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1answer
27 views

How to draw conclusions based on Statistically Equal data sets?

I just have a question about statistical significance that I can't wrap my mind around. So lets say we put out a survey comparing male and females and their frustration levels doing any sort of tasks....
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2answers
45 views

Which statistic test should I use in this situation?

There are 10 questions in which we are comparing peoples' opinion about two conditions, "X"and "Y". Every question was answered by about 90 people who were different than other questions' respondents. ...
1
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1answer
31 views

merit of t-test vs repeated measures

In a cohort study, patients have been enrolled for a new method of treatment of a condition. The measurement of interest, for example, tumour size is taken at baseline (BL) ie before treatment, the ...
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0answers
34 views

Relationship between t-test and normality

I haven't been able to find a definitive answer to my question in previous topics, so I'll post it here. I am sure this is a trivial question for many, but I do not have ny formal training in ...
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0answers
18 views

Debated boss over Performing T-Test on a percentage with changing population size [closed]

My boss asked me to perform a T-Test to test the significance for a certain metric we use called conversion rate. Each month we get a number of people who register for a car sharing service and of ...
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0answers
15 views

Kolmogorov Smirnoff test result vs paired t-test result

I have a set of medical data which contains two samples taken in different time periods. Although the samples do not strictly contain the same people in each group, a large proportion in each group ...
0
votes
1answer
32 views

Paired-t test for comparing two subgroups selected from the same underlying population?

Say I have a total population of N=100. Algorithm #1 is based on some predictors and it selects n1=10 subjects (i.e., subgroup #1). Algorithm #2 is based on another set of predictors and it selects n2=...
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0answers
11 views

Significance test for binary classifier with varying feature sets

I have done binary classification using an SVM with different feature sets and wish to evaluate whether the results obtained on the test set with each of these feature sets are statistically ...
-1
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0answers
32 views

Using $H_0$ to calculate a $p$-value or critical value in a $t$-test

I seem to have trouble calculating (or rather, understanding) $p$-values or critical values when using a $t$-test or sometimes in a normal test. From what I know, the $p$-value is the probability of ...
1
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2answers
56 views

Testing the general linear hypothesis: $H_0: \beta_1 = \beta_2 = \beta_3 = \beta_4 = \beta$

Again, we are testing the linear hypothesis; $H_0: \beta_1 = \beta_2 = \beta_3 = \beta_4 = \beta$ for the model, $$y = \beta_0 + \beta_1x_1+\beta_2x_2+\beta_3x_3+\beta_4x_4+\epsilon$$ I know how ...
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0answers
9 views

Event study output interpretation [closed]

Is there someone who would help me to interpret the output of my event study? The event window is 5 days before and after the event. What does the t-value tell me? I knoe the t-test, but I thought I ...
0
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0answers
31 views

Which test to use? Chi-sq?

I am trying to test kids behavior towards fruits (Banana, Apples, Pears, and Kiwis). At the entrance, two fruit packets (one on each side- left and right) were kept. Kids could take any one packet or ...
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0answers
21 views

Statistical analysis techniques for pre and post repeated measures

I am trying to understand which is the appropriate statistical technique to use for the below experimental design: Design: I have two groups - an intervention group (that took an action, eg increased ...
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4answers
59 views

Frequencies/percentages different from zero - which test?

I conducted an experiment and had participants indicate binary judgments by either pressing "1" or "0" when seeing different types of stimuli. Now I want to test whether the proportions of number ...
0
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0answers
15 views

Do independent t-tests on multiple dependent variables for the same subjects need correction for Type I error?

My experiment has one independent variable with 2 levels (sham & surgery) and I have run a PCR experiment on several genes for the subjects in each group. So, each gene is its own dependent ...
2
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2answers
74 views

R lm output - t values and Pr(>|t|) don't correspond

I have just run a lm in R and here is the output: ...
2
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1answer
49 views

Basic question on difference between two means

Can someone help me understand this regarding the difference between two means? Suppose the mean height of US males is 70 inches with a standard deviation of 4 inches and the mean height for US ...
0
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1answer
26 views

Comparing the results of 2 different type but identical samples from 2 devices

I have 2 columns of of the concentration of fat in fish which is measured by 2 different labs. I need to know if the difference of the results from these 2 labs are statistically significant. The data ...
0
votes
1answer
33 views

Paired t-test of a non-normal data with sample size 66

I have a paired data with n=66. I understand that normality condition of differences data should be met to conduct a paired t-test. However, from the histogram, it doesn't appear so normal. The p-...
1
vote
1answer
47 views

What statistical test to use if analyzing the effect of brands of Soda on their phosphorus content?

As explained in the title, I was wondering what kind of statistical test one should use to analyze the phosphorus content of different brands to see if there is a meaningful statistical difference ...
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0answers
12 views

Test for difference in absolute means, while accounting for full range of variability (+ & -)?

I need a statistical test for whether there is a difference in expected means between two samples, A and B, on the absolute scale, i.e.: Null hypothesis: |E(A)| = |E(B)| A & B are measures of ...
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0answers
65 views

How much better does one distribution approximate a value than a second distribution?

I have two samples (see graphic below), and I would like to know with what degree of certainty I can claim that one of them deviates less from the value 1.0 than the other. I am aware of this ...
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0answers
22 views

Are there occasions when both the two-sample t-test and the Wilcoxon rank-sum test are appropriate?

As the title says, Are there occasions when both the two-sample t-test and the Wilcoxon rank-sum test are appropriate? What kind of problem would be correct to use both on ?
1
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1answer
53 views

Two-sample T-test

Hi I conducted the research where I measured germination of seeds in different ecological conditions. Each seed sample (one germination data) was exposed to different combination of ecological ...
0
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0answers
13 views

Mean Test Set Performance of LSTM & Evaluation

In the paper "Greff et al, 2017 - LSTM A Search Space Odyssey" they evaluate different variants of LSTM architectures against different tasks/datasets. Could you help me to understand the evaluation? ...
1
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2answers
35 views

How to test if the difference between the means of two groups is more than a given value? [duplicate]

The null hypothesis for the t-test is the means between two groups are the same (i.e. the difference between the means of two groups equals 0). However, my null hypothesis is the difference between ...
0
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0answers
18 views

Insignificant t test or MW U test yet high ROC AUC and vice versa

In SPSS, when I conduct a Student's t test or Mann-Whitney U test on (lots of) variables when comparing between 2 groups, some differences are denoted significant, and others aren't. When I conduct ...