instruction stringlengths 9 38.7k |
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The code below generates the desired output. However, the lack of vectorizing means it runs very slowly. How can I speed it up?
I've put the dput results from part of some indicative data.
Input dputs
StandRef input
structure(list(id = structure(c(43L, 50L, 17L, 45L, 9L, 5L, 49L,
33L, 48L, 39L, 71L, 64L, 44L, 47L, 58... |
We have financial some data (500-1000 samples), which is not normally distributed (well known fact from the literature). I have some ideas to do parametric transformations of this data (using some other data) to produce "adjusted" series. My goal is to find a transformation that makes the series normally distributed (w... |
I understand the logic of alpha adjustment for multiple testing. However, I am confused as to whether this correction should be applied to all tests on a dataset or only the pairwise comparison in question.
For example, I have four pairwise comparisons (male vesus female, married versus other, English versus other lang... |
I am at a point where I stumbled upon something I don't fully understand.
I have to compute the covariance matrix using this formula:
$$\Sigma=\frac{1}{m}\sum_{i=1}^{m}(x^{(i)}-\mu_{y^{(i)}})(x^{(i)}-\mu_{y^{(i)}})^{T}$$
with $$\mu_0=\frac{\sum_{i=1}^{m}1\{y^{(i)}=0\}x^{(i)}}{\sum_{i=1}^{m}1\{y^{(i)}=0\}}$$
and $$\mu_... |
My primary question is how to interpret the output (coefficients, F, P) when conducting a Type I (sequential) ANOVA?
My specific research problem is a bit more complex, so I will break my example into parts. First, if I am interested in the effect of spider density (X1) on say plant growth (Y1) and I planted seedlings... |
I'm not sure if this question is correct, but is there a way to construct a covariance matrix for two vectors that have different lengths? If so, how?
And would it have a size of $(m+n) \times (m+n)$ (assuming the two vectors are of length $m$ and $n$)?
|
I have two matched groups consisting of 22 observations each for a Poisson distributed variable. I am interested in evaluating the power to detect a 20% decrease in the outcome for the second group. I have no idea of the correlation between matched groups and hence will have to assume independence. I am planning on eva... |
Can anybody tell me how to do recency, frequency & monetary value (RFM) modeling & customer value modeling in R?
Also, can somebody refer me some literature on it?
|
I am exploring a multidimensional data set. The variables can be mainly divided into two groups: A and B. I have calculated the correlation (Spearman's rho) matrix of this data set, and found that although the correlation between a variable from group A and one from group B is generally low, there are nonetheless some ... |
Consider data consisting of voting results. Votes can be either individual votes of jury members or aggregated votes by certain communities (professional of geographical). In the end there is a set of data where each row has three fields: Voter, Candidate (the one who collects votes) and Place (or rank, voters put cand... |
A newbie question (please provide detailed answers):
I am trying to use the Kolmogorov–Smirnov test. I managed to calculate the difference between the empirical points and the theoretical distribution $D$ (following Wikipedia). But then I am a bit confused about the test:
Is the null hypothesis that the empirical data... |
I have a question. I have several (e.g. VAR01, VAR02, VAR03 ) variables. They are measured twice, one with an intervention and one without intervention.
I want to test the hypothesis that the greater change in VAR01 (before and after the intervention) will also result in greater changer in VAR03.
Which method should ... |
Given two identically distributed random variables $X$ and $Y$ (need not be independent) from the same (known) distribution (and so, known $\newcommand{\E}{\mathbb E}\E(X)$ and $\E(Y)$) and joint density, $f(x,y)$ and the conditional expectation $\E(X \mid Y)$, is it possible to compute $\E( X \mid X+Y )$?
|
I am conducting a least square regression using the python library numpy. When I run OLS (ordinary least square regression) over just the variable IE6 I get this output (with the key takeaway being that the coefficient is negative):
=============================================================================
variable ... |
I've tried to use R to fit some longitudinal models, mostly via lmer and nlme packages. However, it seems that many standard models are lacking, such as antedependence models or factor analytic models for covariance matrices. These models are readily available in SAS.
Would anyone recommend other packages for the job ... |
I've collected environmental data on the dust level using direct-reading instruments. The outputs from the instruments are concentrations recorded at each minute over 1 hour. The data collected at many locations and locations are grouped into Groups and Department. The data looks like this in wide format
Depart1 Gr... |
I started by Time Series Analysis by Hamilton, but I am lost hopelessly. This book is really too theoretical for me to learn by myself.
Does anybody have a recommendation for a textbook on time series analysis that's suitable for self-study?
|
Does it make sense to use a matrix that is made up of jaccard indexes instead of a covariance matrix and perform principal component analysis on that?
|
Inspired by a comment from this question:
What do we consider "uninformative" in a prior - and what information is still contained in a supposedly uninformative prior?
I generally see the prior in an analysis where it's either a frequentist-type analysis trying to borrow some nice parts from Bayesian analysis (be it so... |
What is the difference between Logit and Probit model?
I'm more interested here in knowing when to use logistic regression, and when to use Probit.
If there is any literature which defines it using R, that would be helpful as well.
|
Please help me understanding basic features of chi-squared test for distribution comparison.
As far as I understand, if we draw two samples from the same distribution, and treat one sample as "observed" and another as "expected" then
most of the time the associated chi2 value will be low and the respective p-value to r... |
Recently I've been building a model using logistic regression. To my suprisise LIFT chart looks better on the validation data than on the training data, the same is with ROC. All variables in the model are statistically significant.
The question is: Is this really a serious problem? If so, what are the methods to dete... |
This may seem a trivial question but I haven't found a satisfactory answer anywhere. I need to compute standard errors in a OLS regression $y = X\beta + u$ in R from scratch. How can I do this without inverting $X'X$ matrix? (The reason is that speed is important.) Suppose that I already have factorized the $X'X$ matri... |
I have read an article and I wonder if that is a proper way to present a McNemar's Test statistics.
The study try to measure the change in knowledge before and after a lesson. They performed McNemar's test to calculate the p-value, and tabulate it.
I don't feel comfortable when reading the table because:
McNemar's test... |
I'm modelling an event with two outcomes, a and b. I have created a model which estimates the probability that either a or b will happen (i.e. the model will calculate that a will happen with 40% chance and b will happen with 60% chance).
I have a large record of outcomes of trials with the estimates from the model. I ... |
Edit: I updated the question to hopefully make it more easy to understand. I think it was overly complex.
I’m having a problem applying hidden Markov models to a game I’m building to learn about programming.
I have a game that tries to intelligently estimate what’s currently in your shopping basket. As a user, you ar... |
I am using the lm() and princomp() functions in R to perform regressions on foreign exchange time series. I would like to weight the regressions (and PCA) such that 50% of the influence on the regression comes from the past 3 months, 25% from the previous 3 months, etc, but in a smooth fashion. Both functions take such... |
If I have a multivariate normal i.i.d. sample $X_1, \ldots, X_n \sim N_p(\mu,\Sigma)$, and define $$d_i^2(b,A) = (X_i - b)' A^{-1} (X_i - b)$$ (which is sort of a Mahalanobis distance [squared] from a sample point to the vector $a$ using the matrix $A$ for weighting), what is the distribution of $d_i^2(\bar X,S)$ (Mah... |
Possible Duplicate:
Trouble applying hidden Markov models
Hi and Happy New Year everyone!
I’m having a problem applying hidden Markov models to a game I’m building to learn about programming. Please note that I think its HMM that I need, based on my problem and progress if there's something else I should be doing t... |
I have a planner that can evaluate N arbitrary states, and calculate their fitness. The domains it evaluates have no explicit "end state", so it has an infinite horizon.
What are good methods for calculating when it should stop evaluating states?
My current approach is to estimate the probability of the next evaluation... |
I have a time series of data (about 300-750 elements, depending on the sample) and a model that has some random residues. I used the Kolmogorov–Smirnov test to make sure that the normality hypothesis can't be rejected, so I assume that the residuals are normally distributed. But now I guess I should test if they are in... |
Let's say that there exists some "true" relationship between $y$ and $x$ such that $y = ax + b + \epsilon$, where $a$ and $b$ are constants and $\epsilon$ is i.i.d normal noise. When I randomly generate data from that R code: x <- 1:100; y <- ax + b + rnorm(length(x)) and then fit a model like y ~ x, I obviously get re... |
If I understand correctly, PCA's principle is very simple:
Calculate data vectors' covariance matrix C.
Solve det(C - e*I) = 0, to find matrix C's eigenvalues e.
Calculate matrix C's eigenfunctions (from those eigenvalues).
FIRST: Is this description correct?
SECOND: Any algorithm for machine-solving of the polynomia... |
Suppose I have a sample from a multinomial distribution $\text{Multi}(p_1,\ldots,p_k)$, where $p_1+\dots+p_k=1$. I'd like simultaneous confidence intervals for the $p_i$'s. That is, for any $\alpha\in(0,1)$, I want to define $\ell_i$'s and $u_i$'s (random variables depending on the random sample) such that
$$
P(p_1\i... |
The world of statistics was divided between frequentists and Bayesians. These days it seems everyone does a bit of both. How can this be? If the different approaches are suitable for different problems, why did the founding fathers of statistics did not see this? Alternatively, has the debate been won by Frequentists a... |
I have a process with binary output. Is there a standard way to test if it is a Bernoulli process? The problem translates to checking if every trial is independent of the previous trials.
I have observed some processes where a result "sticks" for a number of trials.
|
Suppose we have three independent normally distributed random variables
$$ X_0 \sim \mathcal{N}(\mu_0, \sigma_0^2), $$
$$ X_1 \sim \mathcal{N}(\mu_1, \sigma_1^2), $$
$$ X_2 \sim \mathcal{N}(\mu_2, \sigma_2^2).$$
Now, define two new random variables $Y_0 = X_0+X_1$ and $Y_1 = X_1+X_2$.
Let $\vec{Y} = [Y_0 \;\;\; Y_1]... |
Possible Duplicate:
What is a good algorithm for estimating the median of a huge read-once data set?
Imagine you have a large, multivariate dataset that resides on disk.
Are there any known methods to efficiently compute median with a minimum number of passes through the data ?
I've found a candidate for variance/st... |
I have a series of three dimensional data like so:
1 2 3 4 5
1 0 0 0 0 0
2 0 0.3 0.5 0.3 0
3 0 0.5 1.0 0.5 0
4 0 0.3 0.5 0.3 0
5 0 0 0 0 0
Which is clearly a normal distribution. I want some way to give this as input, and to get as ou... |
We have two time series: $X_t$ and $R_t$, and a model saying that $R_{t+1} = (\mu(X_t) - \frac{1}{2}\sigma^2(X_t))\Delta T + \sigma(X_t) \sqrt{\Delta T} \epsilon_t$,
where $\Delta T$ is given constant and $\epsilon_t$-s are independent normally distributed with zero mean and unit variance. Further we assume that the fu... |
i try to implement a simple gaussian process regression in java. I almost got every step from the book http://www.GaussianProcess.org/gpml .
With my implementation of algorithm 2.1 on page 19 i'm able to produce results but:
I have the strange behavior that all predicted datapoints where i do not have any target tend t... |
Imagine that you have access to a collection of studies in which an age range, a sample size and an "effect" (say, cigarettes per day) is reported. What is the best way to construct a meta-regression of cigarettes per day by age?
The hard part here is to correctly interpolate across these studies with different sample... |
Yesterday's question Determine accuracy of model which estimates probability of event got me curious about probability scoring.
The Brier score
$$\frac{1}{N}\sum\limits _{i=1}^{N}(\text{prediction}_i - \text{reference}_i)^2$$
is a mean squared error measure.
Does the analogous mean absolute error performance measure
$$... |
My question is regarding the interpretation of the percent of deviance explained (and other $R^2$ anaologs or pseudo $R^2$ values for GLMs.
Is this a meaningful summary statistic for models other than Gaussian? That is, is it at least as meaningful/useful as the $R^2$ statistic in the typical OLS regression model. (W... |
Since I had no answer to the second part of this question I would like to ask it again providing some more infos I gathered in the meantime.
Context
We are designing a complete randomized trial in a forest. The plots (experimental units) exhibit natural variability in the response variables. Since we will set up 3 repl... |
I was wondering: is there are a package in R for automated GARCH model selection? I'm thinking of something like what the forecast package does for ARIMA models.
If I implement this myself, would it be appropriate to just do a grid search over the possible parameters for the GARCH and ARIMA parts of the model (using t... |
Is it inappropriate to use odds ratio for groups that are subset of each other? For example, comparing GPA of female students to GPA of all the students. (This is just an example, not what I am really comparing)
This is a part of a larger project, and my main interest in doing this is to show that the result will be di... |
I vaguely recall from grad school that the following is a valid approach to do a weighted sampling without replacement:
Start with an initially empty "sampled set".
Draw a (single) weighted sample with replacement with whatever method you have.
Check whether you have already picked it.
If you did, ignore it and move ... |
I am trying to assess how the degree of CSR activity could change the financial results of a company. For this, my independent variable would be a CSR score (fluctuations of which give me the variations) & my dependent variables would be a few financial indicators.
My issues are:
Can I use multiple regression for this... |
I am trying to read some WinBUGS/OpenBUGS examples to figure out how to specify models. I can't seem to understand where the probabilistic dnorm, dunif etc. functions are sampling from the distribution and where they are calculating likelihoods. Also, does the order of the statements matter, because it seems that the o... |
I have measured students responses on a Likert scale, which measures their perceptions of their classroom teacher' characteristics. I have also gathered their writing samples in the fall and spring and want to predict how students' perceptions of the classroom teacher influence their their growth in writing. My hypot... |
I know that with a model that is not identifiable the data can be said to be generated by multiple different assignments to the model parameters. I know that sometimes it's possible to constrain parameters so that all are identifiable, as in the example in Cassella & Berger 2nd ed, section 11.2.
Given a particular mode... |
I've attached a picture of the time series I'm talking about. The top is the original series, the bottom is the differenced series.
Each data point is a 5 minute average reading from a strain gauge. This strain gauge is placed on a machine. The noisy areas correspond to areas where the machine is turned on, the clean ... |
I am interested in modeling animal captures as a function of environmental conditions and day of the year. As part of another study, I have counts of captures on ~160 days over three years. On each of these days I have temperature, rainfall, windspeed, relative humidity, etc. Because the data was collected repeatedly f... |
I have some data about protein expression levels in a cell. For each identified protein, there is an expression level and an associated p-value indicating the confidence that the protein was identified correctly. Two of the samples were technical replicates (i.e. a single sample was split into two parts and analysed se... |
I have a set of sequential data around of around 12k points. Each is a 1 or -1. They are split something like 53%/47%. I want to test the hypothesis that this sequence comes from a random walk with a constant parameter. What sort of statistical test should I use?
(I'd also be grateful for any book recommendations in th... |
I would like to know how can I write in dlm form ( dlm PAckage by Petris) a state equation like this:
$$a(t+1) = k(t) + F*a(t) + T(t)w(t)$$
where $w$ is $N(0,1)$.
To make it easier I can assume $k$ and $T$ constant.
My question is how can I rearrange it in the way described by "An R Package for Dynamic Linear Models"?
... |
I have read various (seemingly) contradicting statements whether or not AdaBoost (or other boosting techniques) are less or more prone to overfitting compared to other learning methods.
Are there good reasons to believe one or the other? If it depends, what does it depend on? What are the reasons that AdaBoost is less... |
What are the meanings of "stochastically dependent" and "functionally dependent"? What is the difference?
(I saw the usage of the above terms in the paper "Maximum entropy sampling and optimal Bayesian experimental design")
|
I have inter-arrival times of vehicles recorded by a vehicle detection algorithm. I want to find the closest distribution (e.g., Poisson or other) of this data.
How can I do that?
Here is a graph of the inter-arrival times from a crosspost on SO.
|
If we assume that our data points were sampled from the surface of a sphere (with some perturbation), how can we recover the center of that sphere?
In my searching, I found papers on something labeled "spherical regression", but it didn't quite seem like that was doing the same thing. Maybe I just didn't understand ... |
For a particular application I'm trying to specify a model for the level of contact between two communities, similar to modeling migration. I have no data on contact rates between communities, so there's no parameter estimation here - I'm just trying to posit a reasonable model.
The information I have at hand for pair... |
I want to fit lognormal distribution to my data, using python scipy.stats.lognormal.fit. According to the manual, fit returns shape, loc, scale parameters. But, lognormal distribution normally needs only two parameters: mean and standard deviation.
How to interpret the results from scipy fit function? How to get mean a... |
In hypothesis testing, one must decide between two probability distributions $P_1(x)$ and $P_2(x)$ on a finite set $X$, after observing $n$ i.i.d. samples $x_1,...,x_n$ drawn from the unknown distribution. Let $A_n\subseteq X^n$ denote the chosen acceptance region for $P_1$.
The error probabilities of type I and II ca... |
In Chemical industrial, samples are often analyzed multiple times, e.g. 5 samples and each was analyzed 2 times with 10 data points in total. What would be the confidence interval for the mean estimated from these data? The degrees of freedom is somewhere from 4 to 10 depending on the correlation between repeats.
|
I have some data I'm studying where functional data analysis seems
like a promising approach. But having never tackled FDA
before, I'm having trouble wrapping my head around it.
For background, I have Ramsay and Silverman's "Functional Data
Analysis" and Ramsay, Hooker, and Graves "Functional Data Analysis
with R and ... |
The question I'm referring to comes from Stack Overflow:
https://stackoverflow.com/questions/8723652/estimating-number-of-results-in-google-app-engine-query
In short:
With $N$ ordered samples of a uniform distribution, how to better estimated $N$ with $k$th sample info?
How to compute the probability that the $k$th fa... |
First, a general linear algebra question: Can a matrix have more than one set of (unit size) eigenvectors? From a different angle: Is it possible that different decomposition methods/algorithms (QR, NIPALS, SVD, Householder etc.) give different sets of eigenvectors for the same matrix?
Second, regarding QR decompositio... |
Possible warning: basic question ahead.
Let's say that I model whether I wear red shoes depending on the weather. Red shoes, which is my dependent variable, is a dichotomous variable as I either wear them or don't. Weather is a variable with five 'levels' and I'm trying to find the probability that I will wear read sho... |
I have a sample of data which was generated from a continuous random variable X. And from the histogram I draw using R, I guess that maybe the distribution of X obeys a certain Gamma distribution. But I do not know the exact parameters of this Gamma distribution.
My question is how to test whether the distribution of ... |
In R, c(3,1,0) * c(2,0,1) == c(6,0,0). This is not dot product and it's not cross product. First, what is the name for this product, and second, does it work in WinBUGS, OpenBUGS and/or JAGS?
|
My hairdresser Stacey always puts on a happy face, but is often stressed about managing her time.
Today Stacey was overdue for my appointment and very apologetic. While getting my haircut I wondered:
How long should her standard appointments be? (if the customer's preference for clean round numbers could be ignored, f... |
I'm researching some problems in the health/medical insurance sector and would like to use actual probability distributions (or current data) for doing some sort of risk analysis using simple simulations and the like, to see how different types of policies stack up against different people's perception of risk.
I guess... |
I have a set of ordinal data, generated by a hypothetical turing machine. The data consists of a sequence of symbols such as:
LB1, LB2, UU, UB1 ...
The labels have a natural ordering, and the machine "prints" out the symbols at an irregular pace.
I would like to analyze, for the purposes of determining (with a degree... |
How is $1/T$ distributed if $T$ follows a Student's $t$-distribution?
|
Consider me a "naive researcher."
We have a test of 25 items grouped into 5 item types. Each item is correct or incorrect. All items are math questions, but we expected 4 item types to have different language confounds. We have a population of 28 group A and 32 group B. We expected group A to under perform group B in ... |
I have two continuous variables, X and Y, that are correlated - they are not independent. To correct for non-independence, I have a known correlation structure, a matrix S.
If one calls gls(Y ~ X, correlation = S), what I think happens is that, internally, gls() transforms X and Y in some way so that the regression end... |
We ask a set of users to independently detect and annotate all the buildings on a map.
We do not have a priori knowledge about the location or event the existence of buildings on this map.
I would like to aggregate/cluster their annotations in a way that only 'consensual' annotations are taking into account. That means... |
I read this article on "how not to run an A/B test".
And I still don't understand what exactly the author's reasoning is. Can someone dumb it down for me?
I think what it might be saying is that reading the results of my split tests over time misleads me. I want to be able to understand this well enough that I can expl... |
I have exported a model using SPSS (it was generated by the automatic linear model generator).
My question is simple but I cannot find the answer to it:
how do I import and run this model from the exported xml file?
Thanks in advance.
|
I have been recently given a piece of time series data for analysis. I have calculated the average growth rate for infant mortality per 1000 births and have achieved a variance of 60449.1376 and thus a standard deviation of 245.864, how would I interpret this?
The data are annual infant mortality rates per thousand fro... |
I am looking for a library/package/code to do thin SVD in Java. I found a good implementation of SVD in the COLT package for java, but that's not sufficiently robust with large sparse matrices when only a small number of singular vectors is desired. Any ideas?
|
I may be measuring the length of a stick. I then want to see what is the probability of one measurement under a model.
When using a continuous model, the probability of a single number is zero:
$$
\mathbb P( \text{Length}=\text{length} \mid \text{Model}=\text{model} ) = 0 \>.
$$
What is right way to calculate the... |
I am reading Applied Logistic Regression by Hosmer and Lemeshow.
In chapter 1, they defined $D$ as $-2\ln(\text{likelihood ratio})$, which $D$ is also known as the deviance, and $G$ as
$$D(\text{model without the variable}) - D(\text{model with the variable}).$$
I wonder if $G$ also has an alternative name.
Thanks.
|
I use "boot" package to compute an approximated 2-sided bootstrapped p-value but the result is too far away from p-value of using t.test. I can't figure out what I did wrong in my R code. Can someone please give me a hint for this
time = c(14,18,11,13,18,17,21,9,16,17,14,15,
12,12,14,13,6,18,14,16,10,7,15,10)
... |
The setup for this question is as follows. Lets say we have count and denominator data for six different study sites, by month for 12 months. They're all using a uniform diagnostic standard at the time, so theoretically their counts are all roughly the same. The goal of this is to get an estimate of the typical monthly... |
I'm looking for patterns in a signal.
I had used successfully a cross-correlation approach.
However, I found some references to Gibbs sampling approaches for finding patterns.
My question is:
Are both approaches complementary one to the other, or
are they redundant in some way?
|
I have the following column:
Growth
0.1
0.5
0.23
.
0.5
0.67
0.23
0.42
.
.
.
0.12
0.20
Where dots indicate that there was no data available at that time.
Now I want to compute the difference in growth between the current case and the last available case. Thus, in the second last case this should become: 0.12 - 0.42 = -... |
I'm using SPSS Statistics Base 20. Using Analyze $\rightarrow$ Regression $\rightarrow$ Automatic Linear Modeling I've input about 50 variables.
When using no boosting, the reported accuracy of the model is 21%. The software does not tell me what is meant by accuracy, though.
When I then enable boosting and set the amo... |
I have a time series where the x-axis represents hour of the day and the y-axis represents the avgerage value of some variable, say speed of all the cars in New York. I want to bucketise this data (or say cluster) on their Y-axis value. How can I decide the optimal number of buckets and what parameters should I conside... |
I am learning about pLSA (Probabilistic Latent Semantic Analysis) right now, in the hopes of being able to apply it to biomolecular annotation prediction.
I have a very simple question: How do you choose the number of topics / classes to use in the algorithm? I've searched also literature but I did not find anything en... |
How could I discretize the frequency of words found in a corpus that follow a zipfian distribution? Are there standard methods? It should create bins of exponential-increasing size.
My goal is to convert this continuous real frequency into multiple bins to create binary features in Conditional Random Fields (CRFs). I w... |
In the event of a non-significant interaction between X and M on Y, is it sound to suppress the intercept in the graph that illustrates the relationship between X and Y (X being significant). The moderator line in this case will pass through the origin and represent each level of the factor (M) at zero (i.e. male and f... |
I have two bivariate distributions $A$ and $B$. For some new observation $x$, I would like to calculate the probability that it belongs to $A$ and not $B$.
I can assume that $A$ and $B$ are bivariate normal distributions (but if there is a method that doesn't assume that I'd like to know), but I can't assume their cov... |
I have a model that looks like
lm(y ~ lag(x, -1) + lag(z, -1))
So basically, this is a time series regression with exogenous variables, and I want to carry out a rolling analysis of sample forecasts, meaning that:
I first used a subsample (e.g., 1990-1995) for estimation, then I performed a one step ahead forecast, t... |
In this paper
Anderson, M.J. (2001). A new method for non-parametric multivariate analysis of variance. Austral Ecology, 26, 32–46
I found very useful MANOVA approach that can, to some extent, cope with non-normality. I was wondering if it is possible and plausible to include Mahalanobis distances as similarity meth... |
When trying to select among various models or the number of features to include for, say prediction I can think of two approaches.
Split the data into training and test sets. Better still, use bootstrapping or k-fold cross-validation. Train on the training set each time and calculate the error over the test set. Plot ... |
I'm trying to work around the randomForest package limit of 32 levels for factors.
I have a data set with 100 factors in one of the variables.
I wrote the following code to see what things would look like using sampling WITH replacement and how many tries it would take to get certain % of factors selected.
sampAll ... |
Comment: heavily edited, both to clarify and to fix a mistake. First 7 comments below refer to the previous version.
I have an experiment where 3 raters go over the same data 2 times each, trying to make a diagnosis. The second of these two passes serves as the gold standard, and I want to compare the results of the fi... |
Any help would be greatly appreciated.
|
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