# t-test's questions - English 1answer

2.075 t-test questions.

### Calculate the percentile from a T-score

1 answers, 456 views t-test percentage
Is it possible to calculate the percentile from a T-score? If yes, what formula can be used for it, and what other variables (e.g. standard deviation, degrees of freedom, etc.) are needed for it?

### 1 Need help determining which statistical test to use

1 answers, 33 views t-test multivariate-analysis
I am an MD attempting to do my own statistics for a project I have been working on. I have 3 groups (which are comprised of combinations of 2 categorical variables), lets call the groups A+B-, A+B+, ...

### 1 What type of test should I use on my data?

I am testing gas mileage between three brands of gasoline. I am testing on a small population of 10 cars. Hypothesis: Cars using higher grade gasoline will have a significant higher gas mileage than ...

### 3 When should I use a t-test versus an ANOVA?

2 answers, 76 views r hypothesis-testing anova t-test
I have data of bacterial abundances in different treatments (triplicates). The treatments test 3 factors: Location (root/soil), Fungi (added/none), and Insect (added/none). I would like to determine ...

### 4 t test with log transformation

One of my variables to be compared in a t-test is normally distributed, while the other is non-normally distributed. What test should I use? I thought I should do a reflect log10 transformation on the ...

### 1 Very small sample compared to comparatively very large baseline

I would like to know if a small test group (~5 samples) is significantly different from baseline (300-400 samples). I initially considered Student's T-Test, but it seems that I wouldn't be able to ...

### 2 Do I have to standardize my data to calculate variance?

I have 2 groups/samples. Correct me if I'm wrong, but before doing an independent-group t-test we have to verify the homogeneity of variance with Hartley's F-max test. When doing this test, we have ...

### 1 Performing a t-test with discrete (currency) data

I want to perform a 2 sample t-test assuming unequal variances, however my variable is currency. Currency is discrete, however when checking the assumptions of the t-test, I see that the data should ...

### 1 Testing equality of means of dependent samples

1 answers, 35 views r t-test
I have two samples, one is on the stock YUM (which is a constituent of the S&P500 market index) and another on S&P500. Both samples are from the same time period 2014-2018. I computed the log ...

### 1 When to use paired t-test

1 answers, 54 views r t-test
I have two samples where one is a constituent of another, so I have a sample on a stock and a sample on the market index. Should I use the paired t-test or independent t-test to test if the means are ...

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

2 answers, 346 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 ...

### 2 Paired t-test in testing difference between two classifiers

While reading the paper "Approximate Statistical Tests for Comparing Supervised Classification Learning Algorithms", I am confused at Section 3.3 when the authors claim that the paired t-test is not ...

### Role of T-Statistic in a T-Test

0 answers, 26 views hypothesis-testing t-test
I am not sure if my reasoning about T-Statistic is correct. Could please review it? T Test is defined as a test for checking how unlikely a difference between two groups’ averages is occurred because ...

### Evaluate the significance of the relationship among VIX and S&P 500

I have the weekly time series of returns for both VIX and S&P 500. For the VIX I'm looking at 1 week return period (e.g. this is a 5 day return series rolling weekly) For the S&P 500, ...

### Choosing null hypothesis with t-test

I'm studying for my final and came across this practice question. I realized that it's always been the case that $H_0 = 0$ in my homeworks and exams, but I don't think it's necessary. It also seems ...

### -1 How to perform within and between group analysis?

I have a data sampled randomly. I manipulated the data into this format. I am interested in correlation between n_day_order_early and avg_price (both within group and between group). How should I ...

### How to interprete only one class is accepted in single t-test of linear regression

0 answers, 14 views regression t-test
I was doing linear regression on car dataset. One of its column contains 'make' which is category and representing brand like bmw, audi etc. 'make' columns has total 18 class. I built my model, and ...

### 1 Point-Biserial Correlation (r) for non homogeneous independent samples

1 answers, 320 views correlation t-test independence
I am performing an independent t-test, in which the independent variable is the "group" which has two values A and B representing an approach the participants used, and the dependent variable is a ...

### Why can't you use the standard students t-test when auto-correlation is present?

In my job we have a students t-test and an adjusted students t-test which is used when auto-correlation between the current and previous data is present. Why do you have to use and adjusted t-test ...

### $t$-test to compare two differently sized sets of predictions

I am evaluating two models using a testing set. The models are tailored to return a prediction for each instance, only if there is enough evidence that it is highly accurate. On the contrary, if there ...

### P values and t statistics?

I performed an experiment using two different methods on same object, the results of the experiments were Method 1 70,72,70,75 and 77% Method 2 80,81,67,75 and 82% On basis on average I claimed ...

### t-test: double tailed and single tailed [duplicate]

0 answers, 13 views statistical-significance t-test
Why -- under border-line circumstances -- the double-tailed test canNOT reject the null while the single tailed can? Example from stats.yale.edu No medical treatment: Heal time population mean $30$ ...

### Online anonymous pre post survey with no pairing and lesser response in post

So I had not planned for the post survey initially. But now I want to do it. I am sure that the same people (no outsiders) will fill it. But I cannot get the same number of responses or pair them. I ...

### 1 Is a T test the right thing to do?

I have performed a survey which contains 2 logical sets of people (A and B). In my data set there were roughly twice as many respondents in set A as there were in set B. The survey asks "Do you have ...

### How to calculate the p values for a bootstrap regression?

0 answers, 20 views regression t-test python p-value bootstrap
So I have implemented regression with bootstrapping: I sample N times with replacement, and store the coefficient and the intercept. Does anyone know how I can conduct a t test and calculate the p ...

### Correct stats test to run when comparing one subjects encounter rate to 2 other subjects

0 answers, 18 views t-test wilcoxon-mann-whitney
I have an experiemnt which measured the encounter rate between a male brine shrimp and 2 other females, one small, one large in the same tank, at the same time. The male has to activly choose who he ...

### 2 Why does it says data should be normally distributed for analysis, when different test follow its own distribution (i.e. t, Z, F)?

Why does it say data should be normally distributed for statistical analysis when different test follow its own distribution (i.e. t, Z, F)? What does normality have to do with this?

### Which one-sample test would be appropriate for an ordinal scale?

I am conducting a psycholinguistics study for a term paper in which I investigate how young children interpret "ambiguous" sentences such as "The dog ate the food on the table" in my native language. ...

### 2 calculating necessary sample size

1 answers, 949 views hypothesis-testing t-test sample-size
I am trying to use python and online tools to calculate the accurate sample size. However, each way I use I get a different result. This is the data I have from a previous test Control Group Sent:...

### 1 Comparing 2 samples - different population

1 answers, 29 views t-test assumptions
Is it possible to perform a t-test to explore differences in the means of two datasets with different units? One dataset contains ecosystem services measures (units: carbon mass, noise reduction,...) ...

### No Control Group, Should I use ANCOVA?

0 answers, 64 views anova t-test ancova control-group
Design: Participants are randomly assigned to one of two groups. Treatment $1$ or Treatment $2$. All participants are Tested on Matrix Reasoning and Analogies prior to Treatment. All participants ...

### 1 What t-test to use for dependent samples?How to determine if my sample is dependent

1 answers, 38 views t-test p-value
I am new to statistics, but I need to see if results of my findings are significant, but I’m not sure, which t test to use in my case. I have a product page, that may have from 1 to ~10 videos. So, I ...

### How can I test, that stock price changed significantly after certain event?

I need to test whether stock price changed statistically significant after certain event. I got time series of stock price before and after that event. What test or methodology should I use? (not very ...

### Statistic analysis on dependent and simultaneously independent data

Let's assume that I have a datasheet looking like that: ...

### 1 Looking at simple main effects when interaction is not significant?

I have a 2 (time) x 3 (levels of difficulty) repeated measures design. My repeated measures ANOVA yielded a significant main effect of time, but no interaction. From this I can claim that there is a ...

### Significance of difference in proportion

0 answers, 16 views t-test sample-size proportion
I have a set of survey scores for different groups where each question in the survey has a binary outcome: ...

### Can I make comparisons “before - after” only on the average without sigma

0 answers, 9 views anova t-test repeated-measures sample
Is it possible to do comparisons before - after knowing only average values. It is impossible to calculate sigma, because there is no data. Usually data has this ...

### What are the degrees of freedom for the chisquared distribution for comparing values within a likelihood function?

1 answers, 8 views t-test likelihood likelihood-ratio
Let's say I have a likelihood function for a vector X. I get this as dnorm(X, mean(X), sd(X)Obviously the MLE will be the mean here. But let's say I want to ...

### Comparing Means: Multiple Dependent Variables

1 answers, 825 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 ...

### 13 Understanding t-test for linear regression

2 answers, 699 views regression t-test
I'm trying to work out how to perform some hypothesis testing on a linear regression (null hypothesis being no correlation). Every guide and page on the subject I run into seems to be using a t-test. ...

### 1 Test whether a sample is at least a certain number of standard deviations away from a value

Let's start of with an unknown normal distribution $\mathcal{N}(\mu,\sigma^2)$. Often in hypothesis testing, the null hypothesis is something like: "The mean of the probability distribution from ...

### 1 Least significance difference (LSD)

Hi all sorry if I am not very well prepared for this question. I just have a vague idea about what I am trying to achieve without knowing much statistics, but its of urgent nature that is why I am ...

### 1 2x2 experimental design: t-tests vs. mixed anova analysis

1 answers, 1.144 views r anova mixed-model t-test experiment-design
I have conducted an experimental study, with 1 within-variable (time: T1 and T2) and 1 between-variable (group: control and treatment), measuring just one dependent variable. I understand that this ...

### 1 Compare means between months of consecutive years

0 answers, 18 views anova t-test multiple-comparisons
I have sales data of 150 sellers of an Internet website. For each seller I have daily sales for two years, that is, 730 measures, and there are quite a few days in which the sales are 0. On the other ...

### -1 CLM theorem and t-test/MW test

im running a logistic regression concerning voluntary audit (1 = yes, 0 = no). First i want to look at some descriptive statistics and compare my variables to see if there is a statistical difference. ...

### wilcoxon mann whitney or t-test with same results

0 answers, 25 views logistic t-test wilcoxon-mann-whitney
Im running a logistic regression concerning voluntary audit (1 = yes, 0 = no). First i want to look at some descriptive statistics and compare my variables to see if there is a statistical difference. ...

### 1 Is ANOVA redundant when one has specific planned comparisons and is using Estimation over NHST?

I've conducted a 2 (time: baseline, post-training) x 3 (performance: difficulty A, B, C) repeated measures design, and am interested in specifically whether performance during A, B, and C differ at ...

### 1 Can I run statistical tests on descriptive statistics like mean and standard deviation? (i.e. no raw data)

I'm trying to figure out which statistical test to run on my data, but it has been processed so that now I have gathered the mean and standard deviation values to be used instead of the raw data. I ...

### 2 How to test if one value is significantly different from two others?

I'm analysing classroom interaction data. I'm using a simple quantitative index counting the number of interactions of a certain kind. I want to know if it significantly changed between years 1 and 2, ...

### 1 t-test/chi squarred test or mcnemar test?

To what extent does the effect of presence of music differ for the concentration ability in playing a memory recall game in males and females? So basically I had 50 students (25 females and 25 males) ...