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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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Equivalence test for binomial data?

I have two binomial (success=1 and failure=0) datasets and intend to apply a statistical test to show whether they are statistically equivalence or not. First dataset (x) includes around 164 data ...
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5 views

Tests for mediation between Binary DV and binary IV by a continuous mediator

This is my first time working with binary outcomes in R and I'd be grateful for some advice. I've got an experiment where subjects are in 1 of 2 conditions (A or B) and either succeed or fail in a ...
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19 views

Can we use F-Test instead of pair t-test for the given question? [on hold]

Can we use F-test instead of pair t-test? And if not, then why?
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1answer
28 views

Which statistical test is appropriate if we can not measure normality

Say I have two devices that purifies milk, device A and device B. I assume Device B is better and it produces milk that is 5% better than A. If I want to test this assumption, I take 8 sample from the ...
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28 views

T-Test in Excel - two samples, with different number of observations [on hold]

Let us assume that we have two random samples, $X$ and $Y$, where $Y=X+Z$, so $X$ and $Y$ are dependent and have different number of observations. What is more, suppose that $X$ and $Y$ do not have ...
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12 views

How to choose the correct sample and hypothesis test for spatiotemporal observations?

Consider the following scenario: There exist $N=10$ participants in a study. Each participant $i$ is monitored under baseline conditions and later under experiment conditions. That is, the baseline ...
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13 views

Normality assumption for t/z tests

I have what is probably a silly question regarding normality assumptions for t/Z tests. As I understand, t/z tests require that sample data was obtained from populations following a normal ...
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11 views

Repeated measures pre tests and ppst tests

Good day! I'm currently working on the effectiveness of a card game I developed. Lets say that I let my students play this card game for 5 consecutive days then in that 5 days period I provide them ...
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21 views

Comparing two lognormal distributions

I have two lognormal distributions which represent the annual distribution of sales of fiction and non-fiction books, respectively. The sample size of fiction books is much larger than that of non-...
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11 views

Unpaired or paired T-test when comparing before and after effects between two groups

If I have a drug purported to lower heart rate and I give it to a group of volunteers, I would conduct a paired t-test to determine if their HR before is lower than their HR after taking the drug. I ...
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1answer
73 views

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 ...
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31 views

What statistical tests should I use for this between-subject user study?

So, I have performed a between subject experiment, where half of the users used Tool A to perform the Task and the other half used Tool B to perform the Task. Each tool had specific mechanics to ...
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Is a T-test appropriate for comparing two monthly data sets of mean values where one set is a subset of the other?

I have two sets of monthly Consumer Price Index (CPI) values for the period January 2014 through April 2017. One set is the national monthly CPI for Canada and the second is the provincial monthly CPI ...
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1answer
19 views

Which test to compare Vitamin D serum level between malignant and benign tissues

I have Vitamin D levels for both malignant and benign tumor types and I need to compare them. Which test should I use, unpaired t test ? Another question; I have also PSA level ( also continuous data ...
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2answers
25 views

Checking the Assumptions for T-tests

I am in the porcess of checking the assumptions of some data in order to perform a T-Test and had a few questions about how they should be set up. I was able to find the assumptions for a T-test here....
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1answer
25 views

t-test for two random variables

If I want to compare two random variables $X$ and $Y$ both normally distributed with mean 0.4, and 0.3 respectively; and standard deviation 0.05 and 0.04 respectively, what is the p-value that $X > ...
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2answers
43 views

Does the effect size mean the expected difference between the means

I am designing an experiment and want to define the sample size. To identify this, I am setting my significance level to 0.05 and the power to 0.8. My alternative hypotheses says the two means should ...
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2answers
47 views

How to work out p-value if variances of two groups are different?

How do I work out the p value if the variance of my control and experimental group are different? I can't do the t-test anymore. How do I work the p -value out, what method? Also, my two groups are ...
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0answers
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How to test whether the mean of an observed time-series is statistically different from the mean of the predicted time-series?

Let's say I have an observed time-series from $y_1,...,y_T$, as well as an predicted time-series $\hat{y}_1,...,\hat{y}_T$. I want to test whether the mean of observed values $\bar{y}$ is equal to ...
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0answers
17 views

Appropriate statistical test binary variables

Basic questions, I know.. any help is appreciated! I conducted a survey on people with an impairment. This survey was either filled online, or by phone: the respondent could choose. I want to know ...
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1answer
52 views

Which statistical test would you suggest I use?

I'll try to keep my question as short as I can: For my study I will include 30-40 patients. For each patient, I will already have retrospective data for creatinine, a substance found in urine and ...
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1answer
11 views

Test of Signficiance for Win Percentage

I am looking at the win percentage of a teams using 3 defenders versus teams using 4 defenders and would like to see if the difference in means is statistically signifcant and test within R. However, ...
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1answer
33 views

finding p value for pre/post and treatment/control groups (using r)

I need to find p value for a set of variables in a 2 groups (treatment and control) 2-times scenario (same subjects, pre and post). groups have the same n, with different subjects that have been ...
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1answer
37 views

P-hacking and structural equation modeling

SEM involes testing the significance of the relationship of dozens if not scores of observed variables with latent variables. After this, the relationship between several latent variables are tested ...
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1answer
33 views

2x3 weird design

My experiment tests how frequently people in two different countries use different types of computers. Assume, that there are only three types of computers (desktop, laptop and tablet) . I am ...
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11 views

Comparing the same classifier on paired data

I am using a Linear Support Vector Classifier with sklearn for a project of mine and evaluate the performance of my classifier with nested cross-validation (1:1:1 train:validation:test). In particular,...
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1answer
16 views

Calculate critical test value required for statistical significance given sample size and alpha/

How does one calculate the critical t value that will satisfy statistical significance for a given alpha level (.05), statistical test (e.g., paired t test) and sample size? And how does one transform ...
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15 views

Why is it possible to get insignificant F statistic (p>0.1) but significant regressor t-tests (p<0.1)? [duplicate]

My results show significant t-tests but an insignificant F-test. Is this possible or are my calculations wrong?
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1answer
60 views

Advantages of using independent samples T-test over one-way ANOVA for comparing two groups

I'm still confused as to why it is often recommended to use an independent samples T-Test when comparing two means rather than a One-way Anova. If t^2 = F, and the p values are the same, why use a T-...
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1answer
45 views

Statistical test for paired data at multiple time points?

I have paired data (right and left measurements from the same subject) taken at different times. For the sake of the argument let's say the dependent variable (y) follows a normal distribution and we'...
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3answers
27 views

Difference between dependent and independent group designs

It seems to make common sense that a dependent (repeated measures) design would yield a lower critical value for t than an independent sample design since in the former variance should be lower. Yet ...
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0answers
60 views

Is this an appropriate way to compare simulated and measured data with small sample size, and are there alternatives?

I have a probably fairly basic question which I couldn't find an answer to on here or anywhere else. Would really appreciate any thoughts on this :) I am modelling the propagation of sound through a ...
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1answer
64 views

test of two proportions

Apologies for an elementary question - I am trying to understand the solution to the following problem: "Suppose interviews were conducted at two different shopping centers. This two sample t-test ...
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2answers
72 views

R: t.test, am I doing this right?

I have these data: C <- c(6.9, 8.2, 9.4, 9.2, 7.3, 6, 8.6) f <- c(5.4, 7.1, 5.6, 7.6) To find out if C and f are similar or not, I do a t.test: ...
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testing for difference in means across N pairs of samples

I have N different populations. Within each population, I have an equally-sized pair of sub-populations: $(t_j, c_j)$ for $j=1,N$ For each pair in each population, I have the measurement of a mean. ...
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How do I condense multiple lines of code for t-tests? [migrated]

I am working on a simple dataset which is best analysed with t-tests, but there are at least 2 dozen t-tests, which creates a lot of lines of code and many tables! I was wondering if the there is a ...
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13 views

Can an F-Test be worse than the two single T-Tests? [duplicate]

Normally when conducting an F-Test one is hoping the F-Test of all variables is significant although the single T-Tests yield insignificant results. But can the reverse also be true? That is a worse ...
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How to compare the results of different statistical tests?

I don't know if it is a good question or not. Here's the case, say I have a scale/continuous dependent variable and a bunch of independent variables. My ultimate goal is to build a model to predict/...
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2answers
38 views

What test should I use with a non-normal distribution?

I'm working in a small project but I've a problem trying to choose a statistical test to use. I want to contrast the fetal death rate (Total fetal deaths/Total pregnancies) between 4 regions of my ...
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1answer
67 views

T-test in the presence of autocorrelation

I have a time series data and I would like to check if the sample mean is statistically significantly different from zero. I was going to do the t-test, but the t-test assumes independent data, while ...
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How is this mean scale score range calculated?

I have the attached report for a standardized test (data in the report is simulated). I'm wondering how the column Mean Scale Score Range is calculated. Do the lines indicate the limits of 95% of ...
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1answer
69 views

Interpretation of the t.test and Wilcox.test in R

I got two distribution which are not pairs. It's difficult to say that they are also from a normal distribution because they have different length. The distributions of the vectors are, for gas: <...
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1answer
43 views

Greater than 30% outliers in small dataset - what to do? Standard test? Test with outliers removed? Robust statistics?

I have a small-sample dataset representing observations from a longitudinal study. My principal interest is in 'change scores' across three parameters (A, B, C). This requires simple paired t-tests. ...
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0answers
14 views

Perform t-test R two datasets and multiple variables [duplicate]

I have two data sets (two different countries), and for each data set I have 3 variables: 2 independents (years and car model), 1 dependent (sales) To make it more visual it would look something like ...
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1answer
64 views

Different (Welch's) ANOVA tests and post hoc contradict paired tests. Which one to accept?

This is a problem that I think nothing would help but sharing my data here. I have 3 groups (n=7) which are paired. They are concentrations of a chemical compound in different parts fish tissue. For ...
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1answer
85 views

T test two data set 3 variables per data set, can be used? [closed]

I have two data sets (two different countries), and for each data set I have 3 variables: 2 independents (years and car model), 1 dependent (sales) To make it more visual it would look something like ...
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3answers
171 views

Probability that an observation comes from population A or B?

I'm a web developer looking into some basic statistics -- pardon me if I am using the wrong jargon. :) Considering that: I have 2 populations (A and B; each have about 10,000 observations) For each ...
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21 views

When the T stat suggests the null hypothesis should be rejected for a one tail test, but accepted for a two tail test [duplicate]

I would like to ask a question about interpreting the results of a t-test. I am sorry if the answer is obvious and ask you to excuse me in advance. What happens in a situation where: t-stat = 1.91 ...
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3answers
423 views

Non-parametric alternative to simple t-test

I have five numeric variables of two populations (each of them with 60 individuals) and for each of those five variables I want to know if there is difference in the means. I was trying to use a ...
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0answers
15 views

Stuck on which statistical test to use…? (SPSS)

I’m currently analysing some data that I have collected in my postgraduate research and I am struggling to nail down which statistical tests I need to use. I conducted a study on treatment seeking of ...