# All Questions

164,622 questions
Filter by
Sorted by
Tagged with
5k views

### Significant multiple linear regression model with non-significant betas?

In multiple linear regression, let us say that the F test shows that the model is significant. But the t-tests for beta values does not say that the beta values are non-zero. What can we conclude in ...
28k views

### Interpretation of log transformed predictors in logistic regression

One of the predictors in my logistic model has been log transformed. How do you interpret the estimated coefficient of the log transformed predictor and how do you calculate the impact of that ...
206 views

7k views

### Confidence interval for geometric mean

As title, is there anything like this? I know how to calculate CI for arithmetic mean, but how about geometric mean? Thanks.
44k views

### How to do logistic regression subset selection?

I am fitting a binomial family glm in R, and I have a whole troupe of explanatory variables, and I need to find the best (R-squared as a measure is fine). Short of writing a script to loop through ...
2k views

### Correlation analysis and correcting $p$-values for multiple testing

I am investigating the effect of a drug on EEG and cognition in epilepsy patients. We have done EEG and neuropsychological (NP) tests twice, before and after medical treatment. Some of parameters in ...
115 views

### Relationship between MDL and “difficulty of learning from data”

While trying to make sense of MDL and stochastic complexity, I found this previous question: Measures of model complexity, in which Yaroslav Bulatov defines model complexity as "how hard it is to ...
1k views

### Looking for stats/probability practice problems with data and solutions

I am looking for a self-study site on the web that will allow me to verify my understanding of some basic probability and stats concepts and operations. What I would like is a site with data and ...
3k views

### No lrtest() function available in lmtest

I have got a strange problem with using functions which are supposed to be in the libraries lmtest & language R (downloaded from cran.r-project recently), namely lrtest() and pvals.fnc() - however,...
4k views

### Clustered standard errors and multi-level models

Stata allows estimating clustered standard errors in models with fixed effects but not in models random effects? Why is this? By clustered standard errors, I mean clustering as done by stata's ...
4k views

### How should I measure the relationship between a variable containing text and a binomial variable?

I have data in this format: Words,Source,Result pestology Gomel, cheap, 0 cocreating, cheap, 1 munitioner impersonating nonextinct, cheap, 1 Kolomna, expensive, 1 Enyo's snakemouth, expensive, 0 ...
109 views

### Indicators of disease

I have this dataset with size (rows) and shape (columns) and in each cell #disease/#in cell . How would I answer the following questions? Is size an indicator of disease? Is shape an indicator of ...
6k views

### Normalizing data between 0 and 1

I am a novice when it comes to stats, so I apologize beforehand for the simplicity of my question. I trying to figure out the best way to normalize (this may be the wrong term) my data in so that the ...
311 views

### What is the right name for the variant of the Kolmogorov-Smirnov statistic that retains the sign of the difference?

The two-sample Kolmogorov-Smirnov statistic is normally defined as $D = \max_x |A(x) - B(x)|.$ I would like to compute a variant that retains the sign of the difference between the distribution ...
158 views

### How to assess drug effects using annual death rate data?

I am planning a study to collect data of patients dying after brain infection versus number of cases for the next 5 years in 2 cities where they manage the disease with different drugs. Will a year ...
672 views

### Fitting 4-moment distribution with mixture gaussian

I know that Mclust does the fit on its own but I am trying to implement an optimization with the aim to generate a mixture of 2 gaussians with the combine moments as closed as possible to the moment ...
488 views

### Help with deploying a model

The two main packages I use at work are Palisade Risk and SPSS Clementine - they are both quite old versions and I've been supplementing the ability to analyze properly at work with more modern ...
8k views

### What is the probability that a normal distribution with infinite variance has a value greater than its mean?

I got asked something similar to this in interview today. The interviewer wanted to know what is the probability that an at-the-money option will end up in-the-money when volatility tends to infinity....
9k views

### How to set up a two-way mixed ANOVA with a covariate in SPSS?

I wanted to carry out a two-way ANCOVA for my data. However, SPSS isn't liking that I have only one IV. I have One IV: Group (3 levels, i.e. 2 experimental groups and a control group), One DV: ...
40k views

### Help on subsetting data frames using multiple logical operators in R

In R, I am trying to write a function to subset and exclude observations in a data frame based on three variables. My data looks something like this: ...
6k views

### Advice on classifier input correlation

I have a lot of data on previous race history and I'm trying to predict a percentage chance of winning the next race using Regression, kNN, and SVM learning algorithms. Say a race has 5 runners, and ...
2k views

### Is the matrix dimension important for performing a valid PCA?

If $X$ is a $m × n$ matrix, where $m$ is the number of measurement types (variables) and $n$ is the number of samples, would it be correct to perform a PCA on a matrix that has $m \geq n$ ? If ...
385 views

### Detecting reflection in non-orthogonal rotation

I've known that, in orthogonal rotation, if the rotation matrix has determinant of -1 then reflection is present. Otherwise the determinant is +1 and we have pure rotation. May I extend this "sign-of-...
9k views

### Choose factor level as dummy base in lm() in R

Lets say I am regressing Y on X1 and X2, where X1 is a numeric variable and X2 is a factor with four levels (A:D). Is there any way to write the linear regression function ...
5k views

### The use of median polish for feature selection

In a paper I was reading recently I came across the following bit in their data analysis section: The data table was then split into tissues and cell lines, and the two subtables were separately ...
525 views

### Using QDA for Non-Gaussian distributions

I am evaluating a Quadratic Discriminant Analysis (QDA) classifier on a high-dimensionality feature set. The features come from highly non-Gaussian distributions. However, when I transform the ...
3k views

481 views

### Introductory statistics video courses for social scientists

I have just discovered, through this answer, a nice video resource to share with students in introductory statistics courses. The lectures, produced by the Khan Academy, are fairly didactic and well ...
11k views

### Logic behind the ANOVA F-test in simple linear regression

I'm trying to understand the logic behind the ANOVA F-test in Simple Linear Regression Analysis. The question I have is like follows. When the F value, i.e. MSR/MSE...
733 views

### How to find relationships between different types of events (defined by their 2D location)?

I have a dataset of events that happened during the same period of time. Each event has a type (there are few different types, less then ten) and a location, represented as a 2D point. I would like ...
886 views

I'm trying to figure out the usage of the $\chi^2$ distribution. In other words, in what kind of situations it occurs and how is it useful in that situations. I read the wikipedia definition of $\chi^... 9answers 679k views ### How to summarize data by group in R? [closed] I have R data frame like this: ... 2answers 5k views ### Computer game datasets I have been looking for computer game datasets, but so far I've only been able to find the 'Avatar History' dataset for WoW. Are there any other interesting datasets out there, possibly for other ... 0answers 318 views ### References on semi-supervised LDA I'd like to perform semi-supervised LDA (Latent Dirichlet Allocation) in the following sense: I have several topics that I'd like to use, and have seed documents that relate to these topics. I'd like ... 2answers 2k views ### Detect circular patterns in point cloud data For some volume reconstruction algorithm I'm working on, I need to detect an arbitrary number of circular patterns in 3d point data (coming from a LIDAR device). The patterns can be arbitrarily ... 4answers 47k views ### Labeling boxplots in R I need to build a boxplot without any axes and add it to the current plot (ROC curve), but I need to add more text information to the boxplot: the labels for min and max. Current line of code is below ... 0answers 429 views ### Factor analysis: regression equation and residuals I have used factor analysis with regression method. I was trying to develop an index using this regression equation by using the output of the component score coefficient matrix (SPSS) generated for ... 3answers 249 views ### Learning from unordered tuples? EDIT: I reduced my problem to a more specific question: https://math.stackexchange.com/questions/26573/ But I am still interested in other ideas. Let's say our data is generated by$$Y_i = f(X_i) + \... 2answers 4k views ### Why is the null hypothesis always a point value rather than a range in hypothesis testing? This is somewhat related to another question that I asked. The question I have is, when doing hypothesis testing, when the alternative hypothesis is a range, the null hypothesis is still a point value.... 2answers 1k views ### Hypothesis test for whether correlation coefficient is greater than specified value? I want to test whether a correlation coefficient is greater than 0.5. What should the null and alternative hypothesis be? Should I do a two tailed test or one tailed test? Thanks 3answers 443 views ### How to assess effect of intervention in one state versus another using annual death rate data? I am a beginner in statistics. I have these unpublished data (cases and deaths) of a disease for 7 years (2004-2010) from 2 neighbouring states. The study was started in 2004. State 1 and State 2 ... 3answers 5k views ### “Correlation” terminology in time series analysis From basic statistics and hearing "correlation is not causation" all the time, I tend to think it's fine to say that "X and Y are correlated" even if X and Y aren't in a causal relationship. For ... 2answers 952 views ### Most powerful GoF test for normality It's well established that both Anderson-Darling and Shapiro-Wilk have a much higher power to detect departures from normality than a KS-Test. I have been told that Shapiro-Wilk is usually the best ... 2answers 6k views ### Is it possible to use kernel PCA for feature selection? Is it possible to use kernel principal component analysis (kPCA) for Latent Semantic Indexing (LSI) in the same way as PCA is used? I perform LSI in R using the ... 1answer 3k views ### Post hoc comparison in two way ANOVA with covariate using R Does any body know how to run a post hoc comparison in a 2X2 ANOVA with covariate in R. multcomp package seems very nice but I could not find clear answer or example to my question with this package. ... 3answers 3k views ### Is Bayesian statistics genuinely an improvement over traditional (frequentist) statistics for behavioral research? While attending conferences, there has been a bit of a push by advocates of Bayesian statistics for assessing the results of experiments. It is vaunted as both more sensitive, appropriate, and ... 1answer 647 views ### Bayes classifier Given the prior probability of 2 distributions,$N(x,y)$and$N(a,b)$, where$N(\mu,\sigma^2)\$: How do you make a decision rule to minimize the probability of error, if the prior probabilities are ...

15 30 50 per page
1
â€¦
3246 3247
3248
3249 3250
â€¦
3293