# t-test's questions - English 1answer

2.188 t-test questions.

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

1 answers, 40 views statistical-significance anova t-test
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 ...

### 1 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 1 than the other. I am aware of this question but I find ...

### 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 ...

### T-test - (2-tailed) is not significant? What conclusion can I make from this table? [on hold]

My hypothesis was: 1_ Higher comprehending score for mothers vs fathers 2_ No difference on distancing score for mothers vs fathers My teacher did the SPSS part so I'm not exactly sure if this ...

### 1 Paired samples t test in Python

1 answers, 31 views t-test python paired-data statsmodels
I'm trying to conduct a paired samples t-test in Python (statsmodels package), but I don't see a function for it in their documentation. The closest I can find is ttost_paired, but I don't think its ...

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

0 answers, 21 views mathematical-statistics t-test
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 Two-sample T-test

1 answers, 49 views t-test population
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 ...

### 4 Comparison of two Simpson indices using t-test

2 answers, 1.870 views t-test diversity
I would like to compare two Simpson Indices from two different populations. I have calculated their variance, as it is done in the original paper by Simpson regarding measures of diversity and I have ...

### 6 Can a paired (or two group) t-test test if the difference between two means is less than a specific value?

1 answers, 316 views t-test paired-data
In t-tests (paired or independent) we test if the difference in means if 0 (or another value). I'm wondering if it's possible to instead test if the difference is less than x?

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

2 answers, 32 views t-test
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 ...

### In R: t test with two explanatory variables [on hold]

1 answers, 31 views r t-test
Hi trying to figure out how to incorporate two explanatory variables in a t-test. I am trying to figure out if there is a difference between male and female number of promotions. And if there is a ...

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

0 answers, 15 views t-test spss roc wilcoxon-mann-whitney auc
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 ...

### 1 t-test for differently-sized sample sets

First, Please understand my lack of English skills. I have a problem dealing with statistical hypothesis testing. I'm in a situation to evaluate two independent samples t-test. There are two ...

### How to Control the Type-1 Error Rate for T-Tests Used to Understand Sig. Interaction Effects

Basically, I ran a repeated measures ANOVA between groups R and D with one within-subjects factor with 2 levels. A significant interaction was found. To understand what was driving the interaction I ...

### Dependent variable as MEAN of proportions- treat as continuous?

0 answers, 18 views t-test
I have two dependent variables, one is a mean percentage and the second is a mean duration. I understand that if your dependent variable is a proportion, you cannot treat it as continuous, for example....

### t-test or paired t-test to detect drift for suicide prediction

Context and data I am studying suicides among the military. I created a table that aggregates certain metrics (number of holidays, number of hours worked, etc...) for each officer, for each month ...

### 22 Group differences on a five point Likert item

6 answers, 22.441 views t-test ordinal-data likert scales
Following on from this question: Imagine that you want to test for differences in central tendency between two groups (e.g., males and females) on a 5-point Likert item (e.g., satisfaction with life: ...

### 1 t test for checking if slope β is -1

2 answers, 52 views regression hypothesis-testing t-test
I want to test if the slope of a regression line is -1. I used the t test as such: t = β-(-1)/SE(β) where β is the slope coefficient and the SE(β) is the standard error of the slope coefficient. I ...

### 3 Comparing two computer generated datasets

I have created an artificial stock market where different groups of traders trade with each other and therefore influence the asset price as well as the returns on the asset. The model generates 10k+ ...

### 4 Statistical test to perform on species diversity / Simpson's diversity index

3 answers, 6.608 views t-test ecology diversity
I have a set of data from each of the two sites I am measuring for plant species diversity. I plan on using the Simpson's diversity index (SDI), which combines species richness (number of different ...

### 12 Should I use t-test on highly skewed data ? Scientific proof, please?

I have samples from a highly skewed (looking like an exponential distribution) dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want ...

### 1 Analysing pre-and-post intervention study with anonymous responses

1 answers, 17 views t-test likert
The study I am analysing is a pre-and-post intervention questionnaire of students' views before and after studying a module. The questionnaire was distributed in three different geographical locations,...

### Determining If a certain value could be rejected at specific confident level for two methods?

We have performed a test to determine the calcium level in the blood. We were taken replicate measurements for the old method A and for the new method B which we tested to find the calcium level in ...

### T-tests vs multiple comparison tests vs bonferroni in ANOVA?

I'm taking a course in experiment design and I'm having a hard time grasping the comparative usefulness of t-tests, multiple compariseon tests and bonferroni methods. I understand that in using ...

### Calculating Cauchy prior

0 answers, 19 views r bayesian t-test cauchy
I've recently used the package BayesFactor in R with the default priors scale r. I have been advised to adjust the Cauchy width based on some pilot data rather than ...

### 1 comparison of two mean curves

I have two mean values based on the same sample of people, call them $x_1$ and $x_2$. I know that to compare two means, I would usually use a t-test. However, what I have is a plot of each against a ...

### 1 Statistical test of stock returns product

1 answers, 326 views statistical-significance t-test finance
Say I have a sequence of stock returns: $X_1, ..., X_n$. Then I make a sample of products: $X_1X_2, X_2X_3, ..., X_iX_{i+1},..., X_{n-1}X_n$ How to test, if the sample mean is significantly different ...

### Unequal Sample Size

1 answers, 389 views t-test sample-size
i have unequal sample sizes for my experimental and control group. can i just simply pair the samples from both groups with similarities (example, similar pre-test scores and gender) so that I can ...

### t-test versus One-way ANOVA

2 answers, 794 views anova t-test
I have a 50 question/Likert style survey that is broken into 7 subscores. I am surveying two groups (teachers from four-day schools and five-day schools). For each of the subscores, should I run a ...

### How to test for difference in weighted proportion difference? (and average weighted proportion differences)

Suppose I have a survey where respondents rate different questions as positive (1), negative (-1), or neutral (0), and their responses are given a different weight based on which job they have and ...

### 2 Biological and technical replicates for statistical analysis in cellular biology

These are questions regarding basic statistics/reporting in biology. I have already read a couple of articles on this subject, but couldn't find a clear answer applying to my research. I have the ...

### 1 T-test with nested data

0 answers, 22 views r regression anova t-test group-differences
I want to test gender differences in an outcome variable called the willingness to pay. My data consists of records with following three fields: ...

### How to statistically determine if there was sales lift?

0 answers, 15 views t-test
Say my company is about to make some changes that they expect will increase sales and customer acquisition in current markets, what would be the best way statistically to determine if that lift was ...

### 3 Statistical significance of increase in correlation

I have a sample with some individuals, and also three variables measured for each individual, let's say $A$, $B$ and $C$. There is a mild correlation between $A$ and $B$ and a mild correlation ...

### 1 Comparing the means of 6 groups, binary dependent variable

2 answers, 451 views logistic t-test kruskal-wallis
I accomplished a field experiment which results in six differently treated groups (including one control group, each n = 300). Due to randomization all groups are expected to be equal in terms of ...

### How to determine if a variance of population is known in a A/B test?

0 answers, 22 views probability distributions t-test z-test
Our website is a e-commerce platform for user to view and purchase Fashion items. We are going to launch multiple A/B tests to check if the changes in UI could improve the number of views and ...

### 1 What is the null hypothesis in R's t.test() if alternative is not 'two-sided'

0 answers, 59 views r t-test
recently I wondered about the correct formulation of the null hypothesis in R's t.test() function for One-Sample-tests. Let's assume our known population mean a is ...

### Comparing Means: Multiple Dependent Variables

1 answers, 1.006 views t-test manova z-test
I am using school-level data to compare mean scores for two groups (Group A schools and Group B schools), as measured by a series of indicators: 1) grade-level exam percentile, 2) percent of male ...

### 1 How are the degrees of freedom in the emmeans package calculated? - R

1 answers, 22 views r t-test lme4-nlme post-hoc lsmeans
Let us look at some sample data for 5 hypothetical subjects. ...

### Which test to use when comparing diagnostic performance of doctors with and without a computer assisted diagnostic support tool?

0 answers, 11 views t-test mcnemar-test
This will seem very basic so my apologies. Lets say I have 10 doctors who are inexperienced diagnosing cancer in 100 patients. 50 patients have cancer and the other 50 do not. The doctors provide a ...

### 1 Test the difference between average value of 2 random variables

I am doing an exercise on marketing analysis to determine the strategy that a brand should follow based on historical weekly data collected from supermarkets that sell the brand (let say brand1) and 4 ...

### 14 Comparing two classifier accuracy results for statistical significance with t-test

I want to compare the accuracy of two classifiers for statistical significance. Both classifiers are run on the same data set. This leads me to believe I should be using a one sample t-test from what ...

### Help picking a test for time-series data

0 answers, 11 views anova t-test
I am new to stats and looking for help figuring what is the best test to compare two groups across two time periods. I am working with vegetation abundance data at two locations in two different years....

### 3 What is not normal distribution?

I am running analyses for my dissertation and just got myself in a muddle. I am running descriptive stats to determine whether to use paired t-tests vs Wilcoxon signed rank tests. I've read that it ...

### Which method should i use (comparison of two samples from UK general election with very different sizes)?

(edited version) I have a dataset of UK general election results and want to compare two groups on some criteria (education, health etc based on 2011 Census). These are the groups: the seats gained ...

### 3 Poisson Regression vs. T-test for Balance

I have many subjects that were cluster-randomized to a treatment group and to a control group. I want to check the age balance of the groups following the randomization - e.g. whether there is a ...

### Calculating one-and two-tailed t-tests manually in R

0 answers, 24 views r confidence-interval t-test
I have two samples d1 and d2: ...

### t-Test = intersection between two distributions?

1 answers, 22 views t-test
Is it correct that the p-value of the t-Test is equal to the intersection between two normal distributions? \$\Rightarrow p\text{-value} = \frac{\textit{intersection between N1 and N2}}{\textit{union ...