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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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 ...
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20 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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15 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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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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16 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 ...
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18 views

Hypothesis testing and order statistics

I have the following setup. There is a set $S = \{S_1, \ldots, S_N\}$ of $N$ sensors that are probed for readings (once). Each reading is an independent sample from one of the two distributions $r_i ...
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1answer
14 views

Explaining Non-Significant Moderations

Schools often teach us how to conduct and interpret Moderations. What they don't teach us is how to explain why a moderation didn't work out for statistical/methodological reasons. Assuming that the ...
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1answer
41 views

How am I using KS test incorrectly in R?

Here are the codes I input into R: ...
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12 views

how to offer recommendation? comparison of satisfaction between two groups?

My research is "level of satisfaction in relation to customer service: comparative study between 2 fast foods my questionnaire consists of 19 questions. I'm using SERVERF, the 5 dimensions. 8 ...
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1answer
28 views

Root Mean Square error (RMS) to compare two solution methods?

I solved nonlinear reaction diffusion equation in two method, and I want to make comparison between my outputs by using RMS error. The first solution is $u_1$, a $21\times 21$ matrix, and the second ...
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1answer
58 views

Strategy for Analyzing Data

I have been learning about Machine Learning (via Udacity) and Statistics (via Coursera) the past few months and trying to figure out a good way to combine them for a general approach to explaining ...
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2answers
103 views

Mean value of truncated normal distribution

I have a bunch of data where each observation represents an error $\in [0,1]$ (computed error between a variable and it's ground truth). Extra info: These are the results of the difference between a ...
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1answer
10 views

What method should I use to model simplified performance

I have the data of some build times. These builds occur on a cloud and the runtime has been more varied than in the past. One thing that could be occurring is an improper sharing of resources ...
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16 views

Hypothesis Statistical method Query

What statistical method can I use to investigate whether patients who had a history of having drug “X” on a regular basis had significantly different systolic blood pressure (SBP), diastolic blood ...
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1answer
26 views

Can I use independent t-test for my sample? [duplicate]

I want to compare the means of two independent variables, but my problem is the large difference in their sample sizes. One of my variables consists of 560 people and the other only has 29. So can I ...
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0answers
22 views

Test hypotheses regarding the variance and the average

I have the following problem to solve. I confess I have no idea how to solve. Any tips The average time to perform a task has been $100$ minutes, with a standard deviation of $15$ minutes. Was a ...
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30 views

Welch t-test: Exactly when should it be used? [duplicate]

The guidance on this site concerning when to use the Welch t-test is somewhat general in nature (When conducting a t-test why would one prefer to assume (or test for) equal variances rather than ...
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2answers
198 views

Explanation for non-integer degrees of freedom in t test with unequal variances

The SPSS t-Test procedure reports 2 analyses when comparing 2 independent means, one analysis with equal variances assumed and one with equal variances not assumed. The degrees of freedom (df) when ...
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19 views

How should I report the significance of a spline smooth obtained using mgcv in R?

I wish to test whether a spline-based smooth could be replaced by a linear term. I am using the mgcv package in R. Using the example from the helpfile: ...
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26 views

Correct statistical test when people could appear in multiple groups

Thank you in advance for your help. I ran a survey. People first answered a multiple selection question - they could select as many of the choices as they wanted. The question asked them their ...
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1answer
69 views

Questions regarding Binary Logistic Regression

I am very new to statistics and is currently performing binary logistic regression analysis to test null hypothesis for my dissertation. First, both my independent variables and dependent variable ...
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1answer
136 views

Permutation tests: criteria to choose a test statistic

I regularly use permutation tests and love their simplicity. I've learned most from the book "Resampling methods" by Good, in which the author seems quite creative in his choice of test statistics ...
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1answer
6 views

how do I test the relationship between infection and nurse:patient ratio

I am evaluating whether the prevalence of a specific infection in the ICU bears a relationship to the nurse:patient ratio over time. The infections are whole numbers (nominal variable)and the nurse: ...
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3answers
53 views

Specific Hypothesis

I have one sample group. (I know my test statistics is nonparametric.) My null hypothesis is a CI and alternative is ~ . What is your idea for testing this hypothesis?
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Modified $t$ statistic and $\nu$ for Tukey-Kramer test

What is the expression for the modified $t$ statistic for Tukey-Kramer test in terms of sample means $X_i$ and $X_j$ having $n_i$ and $n_j$ number of samples? Is this correct: $t = ...
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17 views

Testing if the mean of one data set is bigger than the mean of the other data set [duplicate]

I have two data sets, i.e., the number of flowers measured in field A and in field B. Each data set has about 40 samples. I want to do a test to check the hypothesis that field A has more flowers than ...
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1answer
67 views

LR test on marginal effect

Say I have the following regression model: $$\text{Wage}_i = constant + α·\text{YearsOfEduc}_i + β·\text{Age}_i + γ·\text{CompletedHighSchool}_i + \mbox{δ·$\text{NumOfSiblings}_i$} + ...
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Selecting optimal model when only smoothed data available?

I have a graph of some (highly nonlinear) experimental spectrum which is obtained by smoothing results of several repeated measurements obtained by different experimental methods. The graph also ...
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2answers
29 views

Is there any good reference which statistical test should be used given study design?

I am looking for a source (infographics, picture, graph, list, book, algorithm or whatever) that clarifies which statistical test should be used when. I mean what do I use when I have two unpaired ...
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1answer
15 views

Null hypothesis of probit model Wald test

Say I estimate the following probit model: $$ins = \Phi(\alpha + \beta_1 age + \beta_2 educ + \beta_3 hg + \beta_4chronic + \beta_5 hisp + \beta_6 lin) + u$$ where: $ins = 1$ for any individual who ...
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1answer
28 views

MCMC-Draws from different MCMC- chains

I have questions about the usage of draws from a MCMC. I estimate a hierarchical bayesian Multinomial Logit model (using bayesm in R). I am interested in the ratio of two coefficients 1 and 2, say ...
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1answer
38 views

Wald test on marginal effect

Say I have the following regression equation: $$Wage_i = YearsOfEduc_i + Age_i + NumOfSiblings_i + u_i$$ How would I go about peforming a wald test of the hypothesis that for an individual with ...
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About Hypothesis Test In Spatial Regression

I'm doing estimation of spatial lag/error model using R package "spreg"/"spdep". But I can't find any method to do hypothesis test after regression. For example, I want to test whether two ...
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83 views

null hypothesis change

I've done loads of hypothesis tests for the mean (normal distribution) where the null hypothesis is of the form $H_{0}=a$. Now I've come across one where the hypotheses are like $H_{0}{\leq}a$ and ...
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89 views

Wilcoxon rank-sum test for multivariate case when pdf is known

I have sample of around 100 of observations. Each of them is the vector of real numbers of size 30. Also I have pdf which I think may describe the source distribution of my sample. The pdf has ...
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15 views

What statistical test(s) should I run to analyse a directed-tree like data?

Suppose I have data of a kind of binary tree format. There are three levels in the three, thus four different leaf nodes. I would like to find the optimal path from the root node to one of the leaf ...
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1answer
56 views

P values depend on researchers' sampling intentions

John Kruschke has written widely on the misleading information provided by p values. I understand nearly everything he says, although there is one aspect I am a little confused about. Kruschke ...
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1answer
10 views

What's the right test to use to find significance in a table of incidence rates?

I have some data about conversion rates on different browsers, as follows. ...
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Testing for consistency in survey data

I have a panel of 6 persons which each have generated 2 recipes (cooking), R1 and R2. I have then asked everyone in the panel to ...
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30 views

Question about Lagrangian Multiplier (Gradient) Statistic of constrained GMM

I am trying to derive the Lagrangian multiplier statistic (GMM version) under a restriction. The question is given below The quadratic form is given by $Q_n(\theta,\alpha)=[m(\theta)', ...
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1answer
105 views

Is Student's t test a Wald test?

Is Student's t test a Wald test? I've read the description of Wald tests from Wasserman's All of Statistics. It seems to me that the Wald test includes t-tests. Is that correct? If not, what makes a ...
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Statistical Treatment for Hypothesis test

What statistical treatment should I used to test my hypothesis (there is no significant relationship or interaction between the 2 variables with respect to their preferences) if I have three samples ...
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206 views

Test to distinguish periodic from almost periodic data

Suppose I have some unknown function $f$ with domain $ℝ$, which I know to fulfill some reasonable conditions like continuity. I know the exact values of $f$ (because the data comes from a simulation) ...
3
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1answer
114 views

How to interpret non-significant interaction term in linear regression?

I have difficulties interpreting an interaction term in a linear regression with regards to my hypothesis. Consider this basic example: H0: Better school grades lead to higher income and this ...
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1answer
21 views

How to compare concentration ratios

I did a spectrometry measurement with the evaluation of the concentration of an element. For the element of interest I've two peaks (with normal distribution). $ C_1 ± \sigma_1 $ where $ \sigma_1 ...
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2answers
63 views

Alternative to z test for massive samples?

I'm trying to compare a number of large data sets (over 3000 samples per set), when I plot histograms of these distributions I can see two which are clearly different and a z-test confirms this, which ...
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50 views

Calculating the Net Promoter Score for poll data on a 1-5 scale

From Wikipedia The Net Promoter Score is obtained by asking customers a single question on a 0 to 10 rating scale, where 10 is "extremely likely" and 0 is "not at all likely": "How likely is ...
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how to compare groups and percentages within

I am new to statistics and would really appreciate help. The people within the groups are different - how do I compare the percentages to see if there is a statistical significance between the groups ...
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1answer
65 views

How to verify if values are from Gamma distribution?

I have a set of numbers generated from Gamma distribution. How can I verify that these values were all randomly generated from Gamma or satisfy Gamma distribution?
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57 views

Two sample $t$ test in R: where did it go wrong?

I am doing two sampled t test on two species of fish. t.test(fish1,fish2) It runs for a year so there are 365 values for each fish, i.e. $(1,0,1,0,0,2...)$ and ...