3
votes
1answer
200 views

Newton's algorithm for a Minimax Procedure

In order to find the minimax solution of a certain problem I have to determine the constant $c$ that provides the root for the following equation: $$l(c)=3\times \left [ 1-\Phi \left( c-75 \right) ...
0
votes
0answers
14 views

test for variance by using chi square test in R

how can i know if these data -> 93, 91, 93, 150, 80, 104, 128, 83, 88, 95, 94, 97 58, 139, 91 provide evidence that the pop variance is greater than 0.05 (a=0.05) by chi square test in R? please ...
1
vote
1answer
54 views

Interpretation of Maximum likelihood estimation

I have some problem to interpret the result of MLE estimation : Is it possible to get some advise about how to interpret it? the log likelihood function : $\sum^{n}_{i=1}\log\left( \phi\left( ...
2
votes
1answer
64 views

Non parametric Wilcoxon Signed Rank test

I have the following data vector(in fact its 2392 data points long): ...
9
votes
1answer
167 views

Testing whether two regression coefficients are significantly different (in R ideally)

If this is a duplicate question, please point to the right way, but the similar questions I've found here haven't been sufficiently similar. Suppose I estimate the model $$Y=\alpha + \beta X + u$$ ...
2
votes
1answer
35 views

Wilcoxon rank sum test methodology

I'm comparing the performance of two algorihtms $A$ and $B$ based on a metric. For each algorithm, I have $31$ independent samples that represent its performance. This samples are grouped in two ...
0
votes
0answers
13 views

SEM for Non-Normal Ordinal Data

In short, I conducted a satisfaction survey in which surveyees are required to answer on a satisfaction scale from 1 to 7: 285 observations, 37 satisfaction variables. Here is an example of what the ...
0
votes
0answers
11 views

R: Shapiro-Wilk test with relation of W and P-Value? [duplicate]

I'm currently learning about the Shapiro-Wilk test for normality and using R for conducting simple experiments. One thing which is confusing me is that I found some results would produce a high W ...
0
votes
0answers
19 views

How Can I Simulate Repeated Significance Testing in R

I work in marketing, frequently running A/B tests on websites to determine which variation is best to serve to site visitors. I would like to be able to run a simulation that highlights the perils of ...
0
votes
0answers
31 views

one way and two ways anova

anova can be used to test the influence of a factor on an output. One way anova is used if we are considering only one factor and two ways anova can be used if we are considering two factors. ...
2
votes
1answer
37 views

example where comparison of three mean anova and t-test have different results

suppose to have sample from 3 groups A,B,C. The hypothesis H0: the mean of the 3 groups is the same can be tested using 3 independent t test. ...
4
votes
1answer
80 views

Hypothesis testing with Neyman–Pearson (finding cutoff quantile of Poisson dist)

I am currently trying to solve a problem that should be very easy, yet I am stumped, and help would be GREATLY appreciated!! The background of the question is this: Q: The number of typing errors in ...
0
votes
1answer
28 views

Testing a prediction hypothesis

I wish to test the following Hypothesis: H = "sales growth from previous year" predicts "sales growth this year" I have the following data: ...
1
vote
1answer
63 views

Using R to simulate a sampling distribution under $H_0$

We wonder if the colors (of which there are 6) in “Fun Pack” of M & Ms are distributed at random. Let us define as our test statistic $T$ (and there are many ways we could choose to do this) as ...
0
votes
0answers
12 views

Detecting poaching by age class proportion - suggested test for detecting decrease in given age class?

My dataset consists of observations of individuals, recording the date and the individual's age class. Age classes vary in bin size: 0-4 5-9 10-19 20-40 Example ...
0
votes
0answers
16 views

Comparing two distributions using Generalized method of moment estimation

If I consider a data X, I want to fit a distribution Y which has a density f(x) but It's not possible to express the moments of Y as function of the parameters. My problem is : 1- to estimate the ...
1
vote
0answers
22 views

Suspicious Friedman test results

My data involves testing 216 experimental units (computational models) for which one factor (the value of a specific shared parameter of the models) is administered in 4 treatments (i.e. the parameter ...
2
votes
1answer
95 views

Hypothesis testing - Wilcoxon test, bootstrapping, or something else?

A colleague has developed a treatment for to "prevent falls" in cognitively impaired, psychiatric patients. Since this would be very useful treatment in this population, we especially do not want to ...
1
vote
1answer
105 views

Which test should be used to compare two mean differences?

Say that I have two groups who received two treatments, and now I want to know if they progressed AND which group progressed more. I first did a paired t-test to know their progress, respectively, and ...
5
votes
3answers
297 views

How do I test if two (non-normal) distributions differ?

I have read about Student's t-test but it appears to work when we can assume that the original distributions are normally distributed. In my case, they are definitely not. Also, if I have 13 ...
2
votes
1answer
102 views

R: power calculation for beta coefficient

I am interested in calculating the power for the beta effect size, for example ...
0
votes
1answer
32 views

Why isn't this code for prop.test giving me the right answer for test statistics?

I have used the following line of code but it doesn't give me the right answer for (chi-squared) test statistic while it gives ...
2
votes
1answer
72 views

Help in understanding how to apply correctly False Discovery Rate adjustement

I am trying to understand how to correctly apply False Discovery Rate when comparing multiple hypothesis tests. Although I use here R code, my doubts are about the procedure, rather than the ...
3
votes
3answers
115 views

Alternatives to Hypothesis Testing in R [closed]

I've been reading a number of articles and blog posts about issues relating to hypothesis testing. While these sources seem to put forth legit problems with hypothesis testing and it's ...
5
votes
1answer
76 views

Friedman test vs Wilcoxon test for binary IV

I'm trying to assess performance of a supervised machine learning classification algorithm. The observations fall into nominal classes (2 for the time being, however I'd like to generalize this to ...
1
vote
1answer
60 views

Ljung Box test in R

I'm new to stats. I want to get clarity about Ljung Box test. Its a omnibus test. I'm using R to test autocorrelations of a time series. Using below command ...
0
votes
1answer
37 views

Interpreting the result of 2-sample test for equality of proportions with continuity correction

I've done 2-sample test for equality of proportions with continuity correction. (This is the second course of statistic I'm studying so I know basically nothing, at least so it feels.) I'm using ...
2
votes
0answers
75 views

Which test to use when comparing variances for data that is not necessarily normally distributed

I am a biologist looking for guidance regarding which statistical test to use when comparing variances in data. I am comparing two theoretical distributions to the experimental data. The data in the ...
1
vote
1answer
51 views

The concept of “average run length” in change point detection

With respect to the change point detection for data stream, there is a concept of "average run length", which is discussed in the CPM package manual: I am not clear why that "average number of ...
3
votes
3answers
242 views

Hypothesis test for difference in medians among more than two samples

Question The test scores of three groups of people are saved as separate vectors in R. ...
2
votes
0answers
48 views

Hypothesis Testing With Only Two Data Points

Let's say I have monthly data on cars on the road and number of car accidents. I want to know whether cars on the road is somehow related to the number of car accidents. Of course, I could conduct ...
0
votes
1answer
79 views

Conflicting Normality Tests

I have been trying to establish whether I could model my data, a set of 90 observations, using the normal distribution. I have tried the Shapiro-Wilk and the Anderson-Darling tests but each came back ...
0
votes
1answer
163 views

p-values different for binomial test vs. proportions test. Which to report?

The following binomial test (exact binomial test) has a p-value of 0.05698, greater than 0.05 by a bit. 95% CI is (0.5698, 0.8077). ...
1
vote
0answers
35 views

Help with hypothesis test and generalised likelihood ratio test

I have two groups of people undergoing a medical procedure, a relapse group and a non-relapse group. The liklihood function is: $$f_n({\bf x} ; \theta) = \theta^{n_u} \exp[-\theta(\sum_{i \in C} ...
0
votes
1answer
93 views

Understanding the results of an F test in R

I am performing the test to see if there is any differences between the preferences of chocolate for male and female students. My null hypothesis is that there is no difference. My data is not ...
0
votes
0answers
28 views

Substitution test for ANOVA?

I am working on biological dataset. Around 20000 genes of each sample are comparing with the same ones in another group in order to find significantly differentially expressed genes. I am comparing 3 ...
1
vote
1answer
75 views

How to describe the failure of this linear modelling?

I have a time series $X_t$, which is shown in the first plot. In the second plot, I am doing a linear regression on $X_t\sim X_{t-1}$. The regression line is very close to $y=x$. But this is tricky ...
0
votes
1answer
59 views

How to distinguish these two linear regressions?

I have two linear regressions. The linear coefficients of both of them are very close to $1$. The first plot seems reasonable linear regression, while the second one is tricky since if the bottom left ...
1
vote
0answers
144 views

Diagnosis of normality assumption and fitting linear regression in R

I am using the data veteran from R package survival. How can I diagnose the normality ...
1
vote
1answer
87 views

Interpretation of hypothesis testing

I have the following sample. Now I have to test: $$H_0\!:\mu=60,\!000 \quad \text{Vs.}\quad H_a\!:\mu>60,\!000$$ I have computed it in R Software But I do not ...
0
votes
0answers
95 views

Mann-Whitney test on two skewed (Poisson) data sets reject H0 but confidence interval is nearly zero

I'm comparing two sets of samples, X=(x1, x2, ...) and Y=(y1, y2, ...), where xn and yn is an integer (discrete number) from 2-14 denoting the count of a certain event produced by n. The sets differ ...
0
votes
1answer
110 views

Two sided permutation test

I'm trying to write a two sided permutation test to test the alternative hypothesis there is a difference in the medians of 2 independent samples. My question is this: am I calculating the p-value ...
5
votes
1answer
180 views

Simulating p-values as a function of sample size

We are trying to prove a very subtle effect occurring in cells after a certain treatment. Let's assume that the measurements are normally distributed. Let's also assume the untreated cells have $\mu ...
2
votes
1answer
260 views

How to calculate the p-value for a binomial test using pbinom?

25 patients receive treatment, and they each get a difference score (After-Before). 18 of them get positive scores. I would like to test the null hypothesis that p=0.5. I know that ...
0
votes
1answer
92 views

How to test a logit model in R?

I'm building a logit model using R and I'm getting a result of 88.9% of accuracy (verified using the ROC [in rattle, evaluation tab] using 30% of my 34k dataset). What kind of tests would be ...
2
votes
2answers
163 views

What do p-values for levels of a categorical variable represent in Poisson regression?

I have a Poisson model with varying densities: set.seed(1) df = data.frame(density = 1:5, events = rpois(2000, 1:5)) If I regress on this, I get that the ...
0
votes
0answers
31 views

Non-random distribution of SNPs (single-nucleotide polymorphisms)

I have a bunch of groups of DNA sequences in which I have observed changes in different regions (block D and H) vs. the rest of the molecule. The data is available as a table like the one below. The ...
1
vote
1answer
39 views

How to test whether variables are more frequently associated than expected by chance?

I have this presence/absence matrix (S2 is missing on purpose). ...
2
votes
1answer
190 views

Is this process an AR(1)?

The following process $X$ is generated as the sum of a structure $y$ and an $AR(1)$ process with $\phi=0.4$ and $\sigma_{\epsilon}^2=1$: ...
1
vote
2answers
105 views

Nonparametric test

To get the power of the t-test I use this R code: pwr.t.test(n=25,d=0.35,sig.level=0.05,type="one.sample",alternative="greater") and for the test of the Pearson ...