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.
3,332
questions
0
votes
0
answers
17
views
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 ...
- 1
1
vote
1
answer
54
views
Stat sig results on underpowered experiment
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 ...
- 97
0
votes
0
answers
7
views
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 $R^M$ ...
0
votes
1
answer
14
views
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 ...
- 1
2
votes
1
answer
50
views
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-...
- 7,717
0
votes
0
answers
7
views
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 ...
- 1,469
-1
votes
0
answers
18
views
I have a 2x2 crossover design comparing 2 treaments but don't have a clue what statistical analysis to use in SPSS
I have a 2x2 crossover design comparing 2 treaments with a washout period in between but don't have a clue what statistical analysis to use in SPSS. I am not that good at statistics since it is not my ...
0
votes
2
answers
29
views
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 ...
1
vote
1
answer
26
views
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 ...
- 49
0
votes
0
answers
14
views
Using a t-test on the whole population to infer impact of a feature on future population of feature adopters? [closed]
I would like to know whether the impact I observe in a population that has adopted a product feature is due to chance, or is significant.
Say I have a whole population of 100 clients (and I make sure,...
- 1
2
votes
0
answers
15
views
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 ...
- 21
1
vote
1
answer
27
views
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 ...
- 11
2
votes
1
answer
35
views
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)
...
- 329
1
vote
1
answer
29
views
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 ...
- 11
0
votes
0
answers
15
views
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 ...
- 1
1
vote
1
answer
31
views
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 ...
- 13
0
votes
1
answer
45
views
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 ...
1
vote
1
answer
8
views
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 (...
- 11
2
votes
1
answer
77
views
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:
...
- 2,381
0
votes
2
answers
45
views
How to use t-test with percentages
I have the following crosstab the percentages. how can I use ttest_ind to calculate individual cell's p-value.
...
- 1
0
votes
1
answer
28
views
When are equivalent TOST test possible?
For my end-of-study work in architecture, i am comparing different reconstruction (~10) distances from reference 3D model.
I'd like to test if reconstruction are different using statistical tests.
On ...
- 1
1
vote
1
answer
47
views
Two not normal distributed samples & unequal sample size
I got two sample sets a training set around 32k rows and I have a test set of 16k rows. I want to test if the two sets are randomly split. I checked the normal distribution and it is not met for none ...
- 19
0
votes
0
answers
24
views
Is my approach correct? Linear model, linear mixed model, or regular t.test?
The experiment:
I am analyzing samples from patients presenting two different diseases (e.g.: Cond_A, and Cond_B). I have 50 samples from each group. I have additional information about these samples, ...
1
vote
0
answers
22
views
Very small sample size alternative to binary response logistic regression for evaluating single-species habitat associations
I'm interested in evaluating the relative importance of different habitat variables on presence/absence of a particular species in habitat patches. I was limited to surveying 20ish sites on account of ...
- 11
2
votes
2
answers
73
views
What to do when comparing mean of two populations and one is not normal?
I have a dataset with two populations (unpaired). First one with 36 observations, second one 74.
The first passes the Shapiro normality test with p-value = 0.1521, ...
- 23
0
votes
0
answers
20
views
paired t-test for data with large variance
I'm making a research plan, but I don't know how to solve the following problems because I don't have enough statistical knowledge. Can I get some help?
Assumption:
let's assume that the red line in ...
1
vote
2
answers
32
views
Is a paired samples t-test suitable in this case?
I have 3 tasks and want to find out which one is more effective (that is, to find which task people performed better in).
Just over 30 people have participated in all 3 tasks, and their performance ...
- 11
0
votes
0
answers
10
views
Choosing the correct statistical test to compare different methods on the same population
In my study I have a single population of 8 participants. I am interested in looking at differences in behavioural data between each subject (the behavioural data being collected under the same ...
- 1
1
vote
0
answers
23
views
Comparing before and after survey using Likert Scale
We are trying to measure if there is a difference on the level of interests of participants before and after I let them play a game. The survey is in the form of Likert Scale where ...
2
votes
1
answer
27
views
What test to compare two frequencies?
In my project I have to study the vigilance behaviour of birds, and I need to determine if adults start escaping from an approaching human more often than chicks. So I have the frequencies of adults ...
- 121
0
votes
1
answer
56
views
Can someone please help me to understand the statistics used in this code in R?
I'm trying to compare the CCS class between two groups, which is a tool to assess chest pain severity graded by physicians on a scale of 1-4 with a higher number indicating greater severity.I was ...
Stania Yalnate
2
votes
0
answers
30
views
Asymptotic distribution of t-test with two coefficients
I have the following CEF:
$$
y_{i}=\beta_{1} d_{i}+\beta_{2}\left(1-d_{i}\right)+e_{i}
$$
And the following assumptions:
$$
d_{i} \perp\left(y_{i}(0), y_{i}(1)\right)
$$
$$
\mathrm{E}\left[e_{i} \mid ...
0
votes
0
answers
11
views
Can I use one-way ANOVA for two and for three groups in order to maintain consistency across different sample types?
TLDR: Some of my larger dataset has two levels, while some has three levels. Is it appropriate to test everything using one-way ANOVAs or should I do some as t-tests and some as ANOVAs (Welch's for ...
0
votes
1
answer
27
views
Assessing the effectiveness of a teaching tool by paired t-test
You have been asked to assess the effectiveness of a new teaching tool. A sample of 25 students from your classes have been tested before and after the provision of the tool, so each student has two ...
- 1
0
votes
1
answer
32
views
Two Sample Independent Test for Proportions (z test or t test)
Context:
I have two independent samples that I want to compare for equality through an AB test.
The metric being evaluated is binary: user clicks or not (proportions).
Question:
I keep reading that z ...
- 169
0
votes
0
answers
15
views
Which Hypothesis Test for AB test with 4 variants
Disclosure: Stat noob trying to understand the basics of ab testing
Context: I'm running an AB test with 3 treatment test to see which one yields the highest click thru rate.
Q: What is the recommend ...
- 169
0
votes
0
answers
24
views
Is there a way of comparing/ evaluating a machine learning model with a recurrent model with a statistical significance test?
Comparing two different machine learning models (to assess if the difference between the mean performance is real or not using P-value and t-Statistic) is possible and strait forward in Python. ...
- 11
1
vote
1
answer
40
views
Compare variance across time
I have an analysis question. Unfortunately my biostats collaborator is no longer involved in the project.
We have a dataset of n=6 people. the study was terminated early due to covid but we are still ...
- 11
0
votes
0
answers
9
views
Type of Hypothesis Test Question
I’m trying to answer if males or females rate “The Office” higher or not. Initially, I was planning on using an independent samples t-test, but I wasn’t sure if that was appropriate since nearly three ...
0
votes
0
answers
10
views
Change paired t test to LMM: while the content tested before and after treatment is different
I'm new to linear mixed model. I'm not sure how to use it if the contents of pre and post test are different.
It's a within-participant design, including two sessions (with treatment and without ...
- 1
2
votes
1
answer
24
views
Testing and conidence interval in a clinical trial
In a clinical trial, let's say I want to test
$$H_0: \mu_1 \leq \mu_2$$
$$H_1: \mu_1 > \mu_2$$
$\mu_1$ belongs to the placebo group and $\mu_2$ belongs to the trt group. I used an independent two-...
- 501
1
vote
0
answers
9
views
How to analyse serial brain sections probed for different proteins (ttests and potenial issue of independance)
Generic scenario: Brains have been collected from two different populations. They then have been cut into thin sections (serially) for the purpose of looking at the expression of proteins in specific ...
- 11
1
vote
1
answer
25
views
Violation of application requierements / assumptions
As far as I know all methods / models making assumptions about data distribution, data scale, etc. but whenever I read a paper (political sciences) the researcher(s) are violating them (some). E.g. ...
- 11
0
votes
0
answers
37
views
Compare two groups in Cox Proportional Hazards model
I have a Cox Proportional Hazards model and I'd like to check if there are statistically significant differences between ECOG groups 1 and 2 (HR: 1.32 vs HR: 2.19). I have thought of doing a paired t-...
- 926
1
vote
0
answers
25
views
Why don't simulated t-statistics seem to have the non-central t-distribution described in the literature?
I am completely baffled.
I'm interested in generating p-values, and specifically p-values for the t test statistic. One slow approach to doing this would be to generate samples of individual ...
- 11
0
votes
0
answers
26
views
How to test for significance with t-test and interaction variables? [duplicate]
I need to answer this question for my Econometrics class: "Does the gender gap differ significantly in urban versus non-urban areas? Test at the 5% level". I think I need to use the t-test ...
- 1
0
votes
0
answers
12
views
How do I interpret t-ratio of interaction variable?
I need to answer this question for my Econometrics HW: Does the gender gap differ significantly in urban versus non-urban areas? Test at the 5% level. If I am not wrong I need to use the t-test for ...
0
votes
0
answers
22
views
T-test with large standard deviation
I have performed a two-sample t test. I am comparing census block groups with a bike lane in the vicinity (n = 608) with block groups with no bike lane (n = 453), in terms of a population deprivation ...
- 1
1
vote
0
answers
33
views
T-testing on sparse data
Problem: I have two stochastic processes, $S_1$ and $S_2$, that frequently are zero, but occasionally have positive values with unknown probabilities $q_1$ and $q_2$. e.g.
$$
S_1 = \{0,0,0,0,0,21,0,0,...
- 11
1
vote
1
answer
53
views
Shapiro Wilk test of normality
I ran my data under JASP and the p-value for the shapiro wilk test of normality was <.001. How do I interpret this?
- 11