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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3answers
65 views

“Reversed” Shapiro–Wilk

The Sharipo-Wilk test, according to wikipedia, tests the null-hypothesis ($H_0$) "The population is normally distributed". I am looking for a similar normality test with $H_0$ "The population is not ...
0
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1answer
21 views

Testing slope differences for in multiple linear regression?

Continuing from a previous question: My three independent variables are related within themselves: $x_1+x_2+x_3=1$. So in order to test if the whole linear model's $p$-value, I should only include ...
4
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1answer
80 views

Why does Pearson's r have a non-normal sampling distribution at high values of ρ?

I read at http://davidmlane.com/hyperstat/A98696.html that [W]hen the absolute value of the correlation in the population is low (say less than about 0.4) then the sampling distribution of ...
0
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1answer
25 views

Should I use the t-test or the Wilcoxon rank sum test given these qqplots and Shapiro-Wilk stats

I have 4 groups and I want to test if the pairwise difference in means are significantly different. There are 6 pairwise differences. The QQnorm plots of the 4 groups look like this: The ...
2
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0answers
16 views

Hypothesis testing on data from a continuous proportion beta distribution

I am interested in identifying factors that influence the proportion of time each of my samples occupy one of two states (imagine it as ON vs OFF) throughout the course of one day. In a series of ...
1
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0answers
20 views

Evaluating close calls with the Wilcon Sum Rank test two sided vs. one sided

I am testing to see if the means of two groups G and R are different. I cannot use a t-test because the data is not normal so I am using the wilcox sum rank test which seems like the non-parametric ...
0
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0answers
16 views

Wilcoxon Rank Sum test null hypothesis

I am doing a Wilcoxon Rank Sum test in R to see if the means of two groups of data (the data is not normal) are statistically different. When I look at the details of the wilcox test ...
2
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2answers
53 views

Test two groups with only sample statistics or without distributional assumptions

I have two sets of samples, A and B. I want to find whether the underlying mean (i.e. if the sample size was infinite) of A is greater than that of B, to a certain confidence (95%). There are two ...
0
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1answer
20 views

Find out if the growth of two populations is statistically different

I am creating an artificial model that will simulate the growth of two populations of bacteria under different conditions. Specifically, I am interested in whether adding a certain compound to the ...
0
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0answers
25 views

Quantitative Analysis [on hold]

The plant manager of a company that manufactures office equipment is attempting to determine the process that will be used to assemble a new ergonomic chair. Two methods (A and B) are under ...
3
votes
1answer
48 views

Chi-squared-like test with absolute instead of squared differences for calculating test statistic

I am looking for a test which works exactly like the chi-squared test but instead of calculating the test statistic as the sum of squared differences of observed and expected values divided by ...
0
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0answers
20 views

what does an average from a non-normal population mean [duplicate]

i have an elemenary question. If I have a non-normal distribution and get the average does it mean anything? Let's assume the distribution is not known. By "mean anything" I mean can I draw ...
3
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2answers
29 views

How to test if 2 means are significantly different for non-normal non-paired data

I have 4 averages from 4 samples and I want to test if the means are significantly different. When I look at the QQ plots and the shapiro wilk test (all have very low p values) the data is not normal ...
0
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0answers
20 views

When the null model performs better than more complex models

Consider a matrix $X \in R^ {n \times m}$ representing $n$ samples and $m$ features. Also consider a matrix $y \in R^{n \times k}$ representing $n$ samples and $k$ target values. $y$ has continuous ...
7
votes
6answers
106 views

What are good examples to show to undergraduate students?

I am going to teach statistics as a teaching assistant for the second half of this semester to CS-oriented undergraduate students. Most of the students took the class has no incentive to learn the ...
0
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0answers
21 views

Hypothesis Testing for small sample

I am a somewhat dubious about how to apply some hypothesis testing for this case or maybe it is not applicable at all. In an undergraduate Algebra course, the Faculty has been using a book from ...
1
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1answer
10 views

Which statistical test for statistical significance of positive result in 5 categories of samples

I have 5 categories rock samples and I am trying to understand how their fossil preservation differs and whether the difference is statistically significant. I determined the presence or absence of ...
0
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1answer
30 views

Is my data normal graphical vs. analytical test

I am trying to determine if my data is normal. I am using R. I run the jarque bera test that has a NULL hypothesis of Normality ...
0
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0answers
10 views

Statistical test to check if mean of two groups are “significantly” same [duplicate]

Is there a statistical test, to check mean of two group is "sigificantly" same. Something opposite to Wilcoxon test. I was thinking may be running Wilcox test and if it not significant, then check the ...
0
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0answers
14 views

Test if two means are significantly different in R [duplicate]

I would like to test if two means are significantly different from each other. I am using R and I do this: t.test(SampleA,SampleB) and I get output that looks ...
0
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0answers
15 views

Comparison of observations in subgroups?

I have two groups, group A and group B. Each group is composed of subgroups, say A1, ..., An and B1, ..., Bm. Within each subgroup we have a different number of observations, say A1 would contain ...
1
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1answer
23 views

Using contingency tables for testing multiple dependencies

I know that I can determine the correlation / association / dependency between two variables (X= smoker, and Y=cancer) using chi-squared with a 2x2 contingency table: ...
1
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1answer
23 views

how to analyze the results for this binomial test?

I have established the following hypothesis: The probability of successfully passing the course in this trial is less than 50% (alternative hypothesis) The probability of failing the course in this ...
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0answers
12 views

F test in random effects panel regression

I'm using random effects panel regression and I've 3 covariates not statistically significant and I want to test if the three parameters associated with those covariates are jointly equal to 0. Could ...
1
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0answers
22 views

Multi-Level (Sparse) A/B Testing

I've been reading some articles about Bayesian A/B testing such as: http://engineering.richrelevance.com/bayesian-ab-tests/ but my application requires a framework for handling sparsity and group ...
0
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0answers
15 views

Does THE discordance test for outliers exist? [closed]

I have looked but can't find 'the discordance test for outliers'. Does this specific test even exist? And if it doesn't, which test would you suggest to measure discordance for outliers?
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0answers
10 views

Hypothesis for customer dissatisfaction

I am doing research paper that contain the hypothesis of "Building conditions generate customer dissatisfaction among buyers and/or renters". Both building conditions and customer dissatisfaction are ...
2
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2answers
100 views

Estimate statistical significance of a feature in a time series

I have a set of time series with events marked in the middle. Following the event there is a temporary dip in the series values followed by a peak so that the area under the curve is 0. ...
0
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0answers
16 views

what type of hypothesis testing can I apply?

I have the following case: There were two classrooms of approximately 25 students each one, and each of these classes was taught by a different lecturer. A couple of years ago both classes were ...
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3answers
38 views

How to test relationship between weight gain and light exposure in crickets

I am a biology major, and will be running a study and am unsure of what statistical test to run. Here is a summary of what we will be doing: We are testing to see if there is a correlation between ...
0
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0answers
10 views

Analyzing whether several categorical variables might have a causal relationship with a dependent variable

I am trying to use some data to assess why certain terrorist organizations claim responsibility for their attacks and why sometimes they don't. I have a data set that contains relevant information so ...
1
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1answer
47 views

how to apply hypothesis testing in this case?

I have some data samples collected about the weight loss (in pounds) for a set of 27 persons: ...
0
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0answers
27 views

Hotelling $T^2$ distribution

Suppose $d \sim N_p(k\mu_0,\Sigma)$ and $M\sim W_p(\Sigma,m)$ are independent. Here $\mu_0\neq 0$ is a known $p$-vector. $k$ (scalar), $\Sigma$ are unknown. Find the distribution of ...
0
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0answers
26 views

Most Powerful Test and Rejection Region of Gamma Distribution

Let $X_1,\ldots,X_n$ be a random sample from a Gamma $(\alpha,\beta)$ population, where $\beta>0$ is a known constant. The rejection region of the most powerful test for $H_0:\alpha=1$ against ...
1
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1answer
34 views

Test if two gamma distributed populations are different

I have data from two populations of different sizes. Both have Gamma distributions with different shapes and scales (as estimated in r): fitdistr(x/10000, "gamma") #186 members shape 0.586219900 ...
3
votes
1answer
41 views

Hypothesis testing: If not a p-value in mixed effect models, then what?

I've been working on a messy, repeated measures data set of endocrine data looking at a small group of variables (after eliminating several uninteresting contenders in exploratory data analysis), each ...
2
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0answers
38 views

Reporting Mann Whitney test rejecting the null hypothesis, but samples have equal medians

I'm using the Mann Whitney test to verify if two population samples are equal. If the p-value is less than alpha (in this case, 0.05) I reject the null hypothesis and use the median of each population ...
0
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0answers
19 views

Comparing means between two groups if dependent variable is a percentage

I have data on recovery rates from several hospitals across the country. The recovery rates are in percentages. I want to compare the mean recovery rate between two groups of hospitals, one that uses ...
1
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0answers
23 views

Can Cox models be used with time-varying covariates?

I work at a hard drive manufacturer. In my project, we have huge sets of testing data of hard drives. Most of them are time-varying covariates. My colleges are using cox regression. I doubt it. ...
0
votes
1answer
36 views

Question related to p-value

when I read Casella's Statistical Inference, the exercise 8.51 is: where (8.3.9) is $p(x)=\sup_{\theta\in\Theta_0}P_\theta(W(X)\geq W(x))$, and $W(X)$ is a statistic s.t. the large values give ...
0
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0answers
16 views

Comparing differences of ratios in 2 independent populations

I have a setting that I think is quite similar to the one described in What type of statistic should I use to compare ratios in my experiment?. I have two independent populations, which were screened ...
0
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0answers
48 views

statistical calculation of evidence for mutually exclusive genes

I have several genes (A,B,C,D) that show different number of subjects having mutations in them: ...
0
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0answers
15 views

Test for autocorrelated variables

I would like to know if there is a good non-parametric test for detecting auto-correlation of one variable between all the observations of my dataset. I have 60 predictor variables for a statistical ...
2
votes
0answers
20 views

Test for independence in 3x2x2 table with small expected cell values

I have three unordered categorical variables. I have made a 3x2x2 table, but I'm uncertain of how to test for independence. The usual manner is a chi-squared statistic, but I think this is ...
2
votes
1answer
42 views

how to get the critical region for a uniformly most powerful test for mean of normal?

I need help in understanding how to construct a uniformly most powerful test using the Neyman-Pearson lemma. Here is an excerpt in my text that I have trouble following: I have no idea how to get ...
2
votes
1answer
36 views

$F$-test for hypothesis $\beta_1+\beta_2=2\beta_3$ in a regression

In a regression $y = \beta_0 + \beta_1 x_1 + \beta_2 x_2 + \beta_3 x_3 + \epsilon$, how do I use an $F$-test to test the hypothesis $\beta_1+\beta_2=2\beta_3$? The standard $F$-test would test a ...
1
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0answers
52 views

Linear regression on continous outcome using categorical predictor vs Logistic regression on categorical outcome using continuous predictor

The title may be a little misleading, but I could not come up with a better one. Feel free to edit it. Say that we have two variables, $X$ and $Y$, where $X$ is continuous and $Y$ categorical taking ...
2
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0answers
17 views

Hypothesis testing for vector of order statistics

I have a process that generates n values and returns the k largest. I would like to test if the results my process generates are ...
0
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0answers
10 views

Replacing FWER corrections with binomial tests

Say I have $m$ hypotheses to test and I'd like to test them using classical hypothesis tests (i.e. with $p$ values) as part of some simultaneous inference at a confidence level of $\alpha$. Rather ...
3
votes
1answer
45 views

Analyzing data while collecting the data

Part of our samlpe has been collected (Phase 1, $n=12$ subjects with measurements pre and post treatments). The remaining sample (Phase 2 with another 8-10 subjects) will be collected in a few months. ...