Hypothesis testing assesses whether data support a given hypothesis rather than being an effect of random fluctuations or some other process described by an alternative hypothesis.

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Why does a confidence interval including 0 mean the difference is not significant?

Could someone please explain why zero being inside or outside the confidence interval tells you whether or not the difference is significant?
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Please help - deriving covariance of $\bar{Y}_{i+}$ and $\bar{Y}_{+\!+}$

Hello all :) I have been stuck on this problem for hours now and help would BE SO GREATLY APPRECIATED:) For a randomized block design, how would I find the covariance of $\bar{Y}_{i+}$ and ...
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9 views

Hypothesis Testing with unidentified standard deviation [on hold]

A survey found that the average communication of male is 35 and the average communication of female is 65. The data obtained from 100 students from 2 samples and that the standard deviation were _ and ...
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20 views

Is Wilcoxon test still valid if there is some shared information?

I have $N$ samples from a population, and to each sample I apply both method A and method B, recording the time each takes to run ($T_A$ and $T_B$, say) I then define a new pseudo-measurement for ...
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19 views

Correlation? Factors affecting academic performance of students based on their gpa? [on hold]

My friend's thesis. just helping her with the data analysis "FACTORS AFFECTING ACADEMIC PERFORMANCE OF STUDENTS BASED ON THEIR GPA" Divided it into: Internal Factors: Class Schedule & parental ...
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29 views

Why is permutation test wrong with variance but correct with standard deviation? [duplicate]

I am trying to understand the limits of permutation testing. Permutation testing seems to be a nice way to test the null hypothesis that two samples were drawn from populations that share a parameter ...
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12 views

regarding the statistics to test the impact of some subset values on a given variable

For a given variable, there is a set of values. We know that these values can belong to different clusters. For instance, a lot of values center around a small value while other values center around a ...
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18 views

The way to evaluate the importance of an independent variable in a regression model

In a regression model, like y~( x1, x2, x3). Is there a test or a way to evaluate which independent variable, x1, x2, or x3, is ...
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13 views

how to evaluate consistency of rankings for n columns

Suppose I have n columns in a matrix (example below has n= 4). Is there a test I can check that the rankings over columns are ...
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32 views

hypothesis test for a boolean combination of alternatives

I have a student (for a high school project) who has conducted an experiment and collected data in the following (simplified) way: id|situation|scoreX|scoreY ...
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18 views

Comparison of multiple means using summarized data

I have means, variances, and sample sizes from three geographical sites but not their raw data such that: ...
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27 views

Is Bonferroni Correction Appropriate for this Analysis?

Suppose I have performed a study wherein I compare a novel intervention (N) against the standard intervention (S). Participants are assigned to N or S randomly, and the study is performed. There are ...
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1answer
22 views

How to present statistical significance results among more than two datasets?

Let us say that we have 5 sets of data: $$ a = (a_1, a_2, \dots, a_{10}) \\ b = (b_1, b_2, \dots, b_{10}) \\ c = (c_1, c_2, \dots, c_{10}) \\ d = (d_1, d_2, \dots, d_{10}) \\ e = (e_1, e_2, \dots, ...
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81 views

Low sample size: LR vs F - test

Some of you might have read this nice paper: O’Hara RB, Kotze DJ (2010) Do not log-transform count data. Methods in Ecology and Evolution 1:118–122. klick. Currently I am comparing negative binomial ...
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22 views

What criterion are used to accept/reject hypotheses in ridge regression?

On what basis might one accept/reject a hypothesis when running ridge regression? For example, if I have five predictor variables as part of a ridge regression... what criterion would I use to accept ...
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12 views

comparison of time values as response variable

The data set I have is a 12 subject Latin Square cross-over design with 2 periods (1 or 2), 2 sequences (AB OR BA) and 2 drug formulation treatments (A or B). The subject response variable is a time ...
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10 views

R Cramer Von Mises test

I am using the cramer's test in R using the "cramer" package. There are some options for the kind of Monte-Carlo-bootstrap or eigenvalue (ordinary, permutation and eigenvalue) and the kernel (Cramer, ...
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30 views

Which statistical test for women height?

Suppose women may have Blue or Red eyes. We make a first cheap research on a 100 women checking just one eye of each woman. So after the research we have results: At least one eye Blue have avg ...
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1answer
28 views

Variance decomposition time series hypothesis testing

I'm doing biological gene expression data. For the genes I analysed, each gene can produce two isoforms, one dominant (Gene isoform 1) one minus can be treated as a by-product (Gene isoform 2). I'm ...
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1answer
33 views

Big difference in p-value from permutation test

I have roughly 60 values of discrete temperature satisfaction votes ranging from 0 to 4. In the figure below I have grouped the votes depending on the daily number of hours the individual occupants ...
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24 views

null and alternative hypothesis testing [closed]

Share with your peers the null and alternative hypotheses for a decision that is relevant to your life. This can be a personal item or something at work. Additionally, identify the Type I and Type II ...
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15 views

Statistics - Air Quality [closed]

I would appreciate help with this question please. An experiment was carried out on air quality at two different locations in the country on 20 consecutive days. Nitrogen dioxide readings (NO2) in ...
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1answer
21 views

Confused Beginner Question: Multiple simultaneous tests and signal pollution

The best way for me to explain the problem might be to just give an instance of our data and the type of test/conclusion I am attempting to draw. Unfortunately as the title suggests, my understanding ...
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6 views

Probability of type ii error of Pareto distribution

We are given the Pareto Distribution is of the form FX(x) = 1 − (1 + x)^(-1/theta) Earlier, it has been derived that the sample minimum from a Pareto function is also Pareto distributed, with ...
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15 views

Comparing treatment vs control for ordinal data, controling for potential confounders?

I am new here so bear with me. I have two groups, Intervention and Control. Patients have answered the question: How are your back problems now compared to before treatment? Much better, ...
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1answer
31 views

5% significance difference

I need help with this question please. To test the effectiveness of a diet 10 patients are placed on a diet for one month. They are weighted before and after the study. Their initial weight is ...
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57 views

Two sample Kolmogorov-Smirnov test for the stochastic dominance

I'm trying to use KS test to determine whether one group of data is scholastically dominates another. So I'm studying dataset regarding performance of companies, which are divided into 2 groups. ...
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1answer
30 views

Testing if a interval scaled variable A and a nominally scaled variable B are independet when A is not normally distributed

We have a variable A which denotes a percentage between 0 and 1. The variable is not normally distributed but has a very left skewed distribution. About 5% of the observations are zero, most ...
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3answers
70 views

Can I do a t-test to test significance? [closed]

I need a statistical test to determine if one group of ten classrooms with different numbers of students in each class has a class average on a test. Group two has 12 classrooms also with different ...
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10 views

Comparing goodness-of-fit across conditions

I have repeated-measures data. Participants complete both Stage A and Stage B (random ordering). I have two complex models, Model 1 and Model 2, which are fit using optimization techniques. Model 2 is ...
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25 views

A/B/C Testing - Aggregate data for comparison?

Let's say I have 3 ads: A, B and C. These ads perform as follows- ...
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54 views

Empirical rejection rate of a wrong null hypothesis -is it the “power of the test”?

I guess this is basic, but it forms part of the holes in my statistics education. What I know is that the power of a hypothesis test is not a fixed magnitude, but a function of various factors ...
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72 views

Goodness of fit (cdf: empirical vs theoretical)?

I have a data-set with n = 90, probably follows the gamma distribution (and others). I used the maximum-likelihood estimation (MLE) to estimated the alpha and beta parameters of the gamma distribution ...
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1answer
40 views

Hypothesis testing based on Likert type data

I know this site is full of similar questions, but either their answers do not apply, or I'm missing something. I have data from a questionnaire. Responses are in the form of Likert items, some of ...
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1answer
159 views

Unusual Terminology in Hartigan's DIP paper?

In Hartigan's DIP test paper, it says A distribution function $F$ is unimodal with mode $m$ if $F$ is convex in $(-\infty,m]$ and concave in $[m,\infty)$. Shouldn't that be a cumulative ...
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14 views

Determine if missing values are informative(due to treatment) or just noise.

I'm not sure if this is those appropriate way to phrase this question. I have two populations of measurements. In my control population I have a quantitative measure of a proteins abundance. I expect ...
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75 views

Simple Time Series Analysis

Suppose we have collected a set of data points $\{a_{t}\}$ at time $t = 1, 2, ..., t', ..., n$. Each data point consists of the following attributes: ...
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33 views

Comparing min and max estimates

What is the most appropriate way to compare two groups of data in which, rather than a single value for each observation, we have two values per subject - a minimum and maximum value? Basically, one ...
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40 views

Hypothesis testing: difference between proportions

I am investigating staff inequality between genders and ethnicities in an institution. I have data on contract types (permanent or fixed term) and pay grades for almost all employees. I want to test ...
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44 views

UMP for $U(0,\theta)$ (simple x simple hypothesis)

Let $X_1,...,X_n $ be iid $U(0,\theta)$. Find the UMP to test $H_0: \theta = \theta_0$ versus $H_1: \theta=\theta_1$, for $\theta_1 < \theta_0.$ Obtain the power of the test. My attempt: We know ...
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When do we “bootstrap” and then use “t-dist” versus just using “t-dist”?

I'm taking a Data Analysis class on Coursera, and we are learning about bootstrapping when you have a small sample size (>30). What I don't understand, is when do you bootstrap and then use the ...
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13 views

Error type I for $X_i \sim Exp(\theta)$

Let $ X_i$ be i.i.d $Exp(\theta)$ for i=1,...,4.We want to test $H_0: \theta =6$ versus $ H_1: \theta = 2$. Consider the following test: $$\text{Test: Rejects H_o} \iff \frac{X_1 + X_2}{2}>4.5$$ ...
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1answer
66 views

Fisher's combined probability test vs Mantel-Haenszel and Breslow-Day

How do Fisher's combined probability test and the Mantel-Haenszel and Breslow-Day approaches compare, when both are feasible? Is one of these approaches preferred when estimating the combined ...
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12 views

Find the standard error in a two-tailed test without knowing the standard deviation

I have an A/B test and I need to find the standard error for each in order to compute the upper and lower bound at a 95% confidence level. The issue is that I don't have access to the individual ...
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116 views

Calculate at .05 level of significance

A research organization claims that the monthly wages of industrial workers in district X exceed those in district Y by more than Rs 150. Two different samples drawn independently from the two ...
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16 views

Help! Stat test to compare groups

I am comparing two counties to see which one has more grandchildren living with grandparents that left the home because of lack of program support. One county has a grandparent support program and one ...
2
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1answer
26 views

How to draw these t-statistics in R

When determining the necessary sample size for a t test of a difference of mean of two populations a good rule of thumb is typically $$ n = 16 {\sigma^2 \over ...
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2answers
36 views

How come Z-test is recommended by some for analyzing A/B tests?

I've been researching the deep underlying mathematics of A/B testing. I understand A/B tests to be Bernoulli trials (conversion / non conversion) and categorical data represented in a 2x2 contingency ...
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20 views

Expected survival time: comparisons when measurements are an average over other measurements?

Set up We have a few types of interventions. For each intervention, a failure occurs randomly at some time $t$ after start for each subject. We take $n$ measurements of $t$ using $n$ subjects, and ...
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18 views

Where to read about how to build a calculator like this one

I am wondering how to build a sample size calculator like this one: http://www.evanmiller.org/ab-testing/sample-size.html Will the intro chapters of a stats textbook cover this? I've taken a couple ...