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Is there such a thing as a fair die? On dice where the number is represented by a scooped out dot, surely that makes a difference? Has anyone done any research?
In fact thinking about it, why would a coin flip be fair? the physics on each side is completely different.
|
I'm using the logistf package in R to perform Firth logistic regression on an unbalanced dataset. I have a logistf object:
fit = logistf(a~b)
Is there a predict() function like on that's used in the lm class to predict probabilities for future data points? Or do I have to manually input the estimated parameters from t... |
Lets' say I have a Poisson distribution for which I use a maximum likelihood defined as:
$P_i=\frac{m_i^{n_i}}{e^{m_i}n_i!}$
where $m_i$ represents the model value of bin $i$ (real, $m_i$> 0) and $n_i$ its observed value (integer, number of counts in bin $i$).
The cumulative likelihood for the whole data set is then:
$... |
I'm new to feature selection and I was wondering how you would use PCA to perform feature selection. Does PCA compute a relative score for each input variable that you can use to filter out noninformative input variables? Basically, I want to be able to order the original features in the data by variance or amount of i... |
Does Matlab provide any facility for evaluating clustering methods? (cluster compactness and cluster separation. ....)
Or is there any toolbox for it?
|
it's my first question on this forum.
I just purchased Probability and Statistics - Basic book from amazon to refresh and learn what I've never learned. I like the book it explains the subject well. However, I got a different result on one of the examples.
Example:
2 fair dice are rolled. What is the probability of ... |
I'm trying to fit a multi-level model where people are nested in groups. V1 is my outcome variable. G2 is my highest level group and G1 is a group nested within G2
m1 <- clmm(V1 ~ 1 + (1 | G2), data = df, Hess = T)
m2 <- clmm(V1 ~ 1 + (1 | G1) + (1 | G2), data = df, Hess = T)
Based on AIC values, m1 is the best fit, ... |
I.e. based on stats of site visiting, clicks, classifying visitors based on what they are interested in, time, day of week etc.
Any frameworks/resources you can recommend?
For example: we have a lot of advertisements with different prices. Task is to build a set of advertisements in a block to achieve the best CTR (in ... |
This is really puzzling...
I have this data which has a lot autocorrelations...
The data is about 60000 data points of 15min data.
I tried fitting it to ARIMA(6, 0, 6) and even GARCH(1, 1) with mean model ARMA(6, 6), still there are lots of autocorrelations in the residuals.
I almost wanted to try ARIMA(100,0,100), b... |
Let's say I collect data from an experiment where for each measurement device, 5 trials are conducted at different temperatures. Each device is calibrated separately, and the 5 trial temperatures are constant across devices. In other words, I have values at Temperature 1, 2, 3, 4, and 5 from each device.
What is an app... |
Suppose I have a die and I throw it a large number of times (a billion times) and have proven that it lands on each side an equal number of times so it is proven to be fair.
Next suppose I started a second round of throwing of the same die and it lands on 1 through 5 say a 10,000 times each and the count for 6 is 100.
... |
I'm simulating data from a logistic regression model:
log(p/1-p)= 0 + X
where $X \sim N(0,\sigma^2)$. After I simulate the data, I fit a logistic regression model to the data and compare the fitted regression coefficients to the actual regression coefficients.
I've noticed that as I increase $\sigma$ (i.e. the varian... |
I have 114 vectors with 6 boolean attributes. I saw that might be several distinct clusters in a simple visualization. K-means clustering on the transformed vectors (true = 1, false = 0) results in roughly the clusters that I had seen in the visualization.
However, I am not sure what the most appropriate clustering met... |
I need to use the output from certain tests like Factor Analysis to compute additional variable like socioeconomic status.
|
Based on this guide to simulating survival times in SAS and R, I used the following code to generate two survival functions:
data simulation;
call streaminit(321);
beta_death = 0.9163; *Simulated ln(HR) of ~ln(2.5);
lambda_death = 0.002; *Baseline hazard of death;
beta_discharge = 0.4055; *Simulated ln(... |
In the proof of Theorem 2.2 from the book by Devroye et al., I don't understand why $g(x) \ne g^*(x)$ implies $|\eta(x) - \tilde\eta(x)| \geq |\eta(x) - \dfrac{1}{2}|$.
Note that $\eta(x) = \mathbb{E}\{Y|X=x\}$ is the regression function, $\tilde\eta(x)$ is an approximation of $\eta(x)$, $g^*(x)$ is the Bayes classifie... |
I am using R, I searched on Google and learnt that kpss.test(), PP.test(), and adf.test() are used to know about stationarity of time series.
But I am not a statistician, who can interpret their results
> PP.test(x)
Phillips-Perron Unit Root Test
data: x
Dickey-Fuller = -30.649, Truncation lag parameter = 7, p-... |
I am particularly interested in hearing thoughts on what are logical next steps in the research agenda of people who are interested in "The experimental approach to development economics" or in the evaluation of policy.
Many people reject the notion that a randomized controlled trial (RCT) can estimate relevant policy ... |
Akaike's model selection criterion is usually justified on the base that the empirical risk
of a ML estimator is a biased estimator of the true risk of the best estimator
in the parametric family, say the family of linear regressors on a m-dimensional variable,
$S_m $
On the other hand, this family, $ S_m$, is known t... |
Short version: I have two time series: steps taken and change in body fat mass. Both are daily data. I am trying the estimate the effect of the number of steps taken on the change in body fat mass. I am especially interested in getting a point estimate and interval for for where the effect goes from positive to negativ... |
I'm rather evangelistic with regards to the use of likelihood ratios for representing the objective evidence for/against a given phenomenon. However, I recently learned that the Bayes factor serves a similar function in the context of Bayesian methods (i.e. the subjective prior is combined with the objective Bayes fact... |
For my thesis there's a big chance that I will need some sort of mixed-effects specification. I have some (non-syntax) experience with SPSS but feel that it won't suffice for my analysis. I have very basic knowledge in Stata and decided to experiment more with that package.
I decided to try and replicate results from ... |
I want to compare three models, one linear-regression-model, one regression-tree-model (from rpart) and one MARS-model (from mda package).
I want to compare the models using a leave one out cross validation using the mean square error and MAPE. I have the following implementation in R:
library(data.table)
library(rpart... |
What would be the easiest way to plot in the same graph, the probability density function or the cumulative distribution function of a distribution, for 3-4 different parameter values.
Let's take for instance the Weibull distribution W(a,b). I would want to plot the PDF for a=1/2,b=20 , a=1/3,b=20, a=1/4,b=20, a=1/5,b... |
I am learning Bayesian statistics for a data mining module. We were given a set of practice questions but no answers and I want to make sure that I am going about Bayes in the right way.
Suppose Manchester United were about to play Arsenal in the Premiership and you assess the probability
of Manchester United winning t... |
I often find myself training several different predictive models using caret in R. I'll train them all on the same cross validation folds, using caret::: createFolds, then choose the best model based on cross-validated error.
However, the median prediction from several models often outperforms the best single model on... |
I'm not sure how this would look. It seems you've have to specify regime breakpoints within the data, right? Or is there some rolling method that could compare window sizes against each other?
Also key, is it possible to do this without specifying a model?
|
Let $X$ be a discrete uniform random variable on the set $\{000, 011, 101, 110\}$ of four binary integers, and let $X_{i}$ denote the ith digit of $X$, for $i = 1, 2, 3$. Show that $X_{1}, X_{2}, X_{3}$ are independent pairwise, but not totally independent.
Can you generalize this example to more than three random v... |
I have data from a experiment that has been repeated 3 times under the same condition. Each time, 5 measurements of each of 2 groups (a control and a treatment) were taken. I want to run a t-test on my data, to infer if there's a signification difference between the control and the treated group.
How should I use ... |
I'm doing sme test using R and linear models.
This is the code I'm using:
> a
[1] 0.10 0.05 0.02 0.04 0.09 0.05
> b
[1] 0.07 0.02 0.08 0.02 0.01 0.06
> c
[1] 0.03 0.03 0.01 0.05 0.06 0.09
>
> r.a
[1] 0.10 0.15 0.17 0.21 0.30 0.35
> r.b
[1] 0.07 0.09 0.17 0.19 0.20 0.26
> r.c
[1] 0.03 0.06 0.07 0.12 0.18 0.27
>
> mod ... |
Please give me mathematical explanation if possible. And also in the book Kothari 2004, it says:
There is also not as much information in ‘n’ observations within a cluster as there happens to be in ‘n’ randomly drawn observations.
Can you also give me mathematical explanation for this?
My second question is why is si... |
I'm analysing the results of an experiment using a mixed (fixed and random-effects) ANOVA with nested effects and I just need someone to confirm that I have the right model.
The effects in the design are:
Product--fixed, 5 levels--this is the main effect of interest
Batch--random, 3 levels--nested within product
Day--... |
I would like to:
i) check if the odds ratios (OR) for each factor level are significantly different.
Edited:
This is the model I used:
NewMod2C <- glm(formula = surv ~ as.factor(season) + as.factor(pgrp) + as.factor(sline)
+ as.factor(tb5)
... |
I am trying to write some codes for distance-based evaluation of point process such as $G$, $F$ and $K$ functions. In the implementation of $K$ there is a case to consider edge effect to have an unbiased $K$ measure. A simple (!) but perfect (also common) solution is to consider the intersection area of a circle drawn ... |
I'm afraid I'm not an expert in statistics, but I have a particular problem I'm interested in solving. I'm pretty sure this area already has a lot of literature, but I'm having difficulty finding something directly applicable to what I'm doing, so it would be great if somebody could nudge me in the right direction.
I'l... |
In the proof of Theorem 6.5 from the book by Devroye et al., how is the last inequality derived?
$$
\begin{aligned}
\mathbb{E}\left\{|\eta(X)-1/2|\mathbf{I}_{\{g(X)\ne g^*(X)\}}\right\}
&\leq \mathbb{E}\left\{\mathbf{I}_{\{\eta(X)\ne1/2\}}|\eta(X)-\tilde\eta(X)|\mathbf{I}_{\{g(X)\ne g^*(X)\}}\right\}\\
&= \mathbb{... |
Given a weighted sum of regression trees, is there an efficient algorithm to find all local maxima ?
(I would tend to think that a gradient based method will find some maxima but it is not entirely clear to me how to ensure that one will find all of them)
|
I have different models namely AR, ARMA, ARIMA for different time series (in data set of 4449)
stationary-3096, Non stationary-1353 , why this classification appears to be?
If I have $AR(p=1-5)$ and $AR(p >5)$ what does my data tell ?,
I have many time series which follows ARMA-1239 best models, some are AR-90 best mo... |
This is continuation for a series of questions (1, 2). I have a data set from an experiment with 2x2 design. A replicate consists of 20-50 normally distributed replicate measurements. Each treatment combination has 3 of these replicates. Measured average response for each replicate seems not to be normally distributed.... |
Let the random point $(X,Y)$ be uniformly distributed on the unit disc $D=\{(x,y):x^{2}+y^{2}<1\}$.
Show that the polar coordinates $R\in [0,1)$ and $\theta \in [0,2\pi)$ of the point are independent.
Can you help me with this exercise please?
|
I'm reading A. Agresti (2007), An Introduction to Categorical Data Analysis, 2nd. edition, and am not sure if I understand this paragraph (p.106, 4.2.1) correctly (although it should be easy):
In Table 3.1 on snoring and heart disease in the previous chapter, 254
subjects reported snoring every night, of whom 30 had... |
For two normally distributed samples, is there a way to test for $H_0: \mu_1=\mu_2$ and also $\sigma_1^2=\sigma_2^2$. I have computed the likelihood ratio, but cannot recognize the underlying distribution.
|
I am working on a project (not homework) and would like to know if I am just fundamentally misguided.
Basically, let say we have some data $Y, X_1$ and $X_2$.... where $X_1$ and $X_2$ are matrices. If I create an orthogonal projection of $X_1$ relative to $X_2$... something like this (R code; please correct me if th... |
I'm hoping that someone could suggest a tool for viewing conditional probabilities withi. I am currently using Weka, but the ability to view the conditional probability tables of nodes within the Network is not the easiest to read.
Any suggestions on tools out there, or perhaps a workflow in R that can help with this ... |
I am trying to come up with a model that can predict movie box office. One factor that is important is competition... I want to model it as a function of several variables, including some that are variables in their own right in this fuller model.
One- if a variable would be counted twice, should I even do it that way?... |
I have a data set consisting of noisy position values of a trajectory of a human hand. I want to estimate a generative model of these trajectories, and the obvious choice is a Kalman Filter/linear dynamical system.
Since the relationship of position/velocity/acceleration is well known, I chose a LDS with 3 latent vari... |
I was reading about cointegration (page 5) and it said
"If a linear combination of combination of a set of $I(1)$ variables is
$I(0)$, then the variables are cointegrated."
Does this mean that any 2 $I(1)$ variables, no matter what they are will definitely be cointegrated? If yes, can you give the proof. If no, c... |
I came across this note from a book: "..the correlation between the active and passive portfolios is greater when the $\beta$ of the active portfolio is higher.."
The author runs regression of active portfolio on passive portfolio.
This does not make sense to me. If I understand correctly, beta in a single variable li... |
I was doing a lot of research into organized crime in East Asia for a project as a favor to an author-friend of mine, and I noticed that there were noted economists and journalists who, in conjunction, estimate the value of black market operations worldwide.
What is the methodology for this? How do these numbers come ... |
I have a simple question about the GARCH model.
We know that the $\alpha$ and $\beta$ parameters of the models are fitted for the local volatility of each time $t$ as follows:
$$\sigma_t^2= \alpha_0 + \sum_{i=1}^q \alpha_i \varepsilon_{t-i} + \sum_{i=1}^p \beta_i \sigma_{t-i}^2$$
with $\varepsilon_t=\sigma_t z_t$ and $... |
Have, let's say, the following data:
8232302 684531 116857 89724 82267 75988 63871
23718 1696 436 439 248 235
Want a simple way to fit this (and several other datasets) to a Pareto distribution. Ideally it would output the matching theoretical values, less ideally the parameters.
|
I am trying to calculate the $R^2$ value for a production constrained spatial interaction model, using Fotheringham and O'Kelly (1989) as my guide.
I get dramatically different values for R-Square, depending on whether I calculate it as r-square <- 1 - SSe/SSt or r-square <- cor(x, y)^2. Is this result expected? Of co... |
In answer to a question on model selection in the presence of multicollinearity, Frank Harrell suggested:
Put all variables in the model but do not test for the effect of one
variable adjusted for the effects of competing variables... Chunk
tests of competing variables are powerful because collinear variables
join for... |
How close to reality is the normal distribtion?
The height of people is supposed to be normally distributed but the probaility of a 30 foot person in a normal distribution is not zero. Does it matter?
|
I'd like to generate a new point which should be uniformly distributed on the interval [a, b) (i.e. including the left extreme value - a and exluding the right extreme value - b). The runif help says:
runif will not generate either of the extreme values unless max = min
or max-min is small compared to min, and in pa... |
Let the random point $(X,Y)$ be uniformly distributed on the square
$D=\{(x,y):-1\leq x\leq 1,\ -1\leq y \leq 1\}$.
Find the distribution function and the probability distribution function of $Z=X +Y$
|
Say I have multivariate normal $N(\mu, \Sigma)$ density. I want to get the second (partial) derivative w.r.t. $\mu$. Not sure how to take derivative of a matrix.
Wiki says take the derivative element by element inside the matrix.
I am working with Laplace approximation
$$\log{P}_{N}(\theta)=\log {P}_{N}-\frac{1}{2... |
I'm trying to understand the behavior of logistic regression in high dimensional problems (i.e. when you are fitting a logistic regression to data with a high number of predictor variables).
Every time I fit a logistic regression with a high number of predictors, I get the following warning in R:
Warning message:
glm.... |
I was wondering how you would generate data from a Poisson regression equation in R? I'm kind of confused how to approach the problem.
So if I assume we have two predictors $X_1$ and $X_2$ which are distributed $N(0,1)$. And the intercept is 0 and both of the coefficients equal 1. Then my estimate is simply:
$$\log(Y)... |
I am a medical student working on a project which requires massive data that are collected manually through data entry operators. Although I am using traditional tool used by epidemiologists, Epi Info, I just wanted to know if anyone could recommend some good alternatives--not necessarily free/open source though prefer... |
Suppose I've a one-way table with three categories (A, B and C), and let $p_a$, $p_b$ and $p_c$ be the true proportion of observations in each category, i.e. $p_a+p_b+p_c=1$. How can I conduct a statistical test on the hypothesis "$p_a$ is the largest among the three", i.e. $p_a > p_b$ and $p_a > p_c$?
Thanks!
|
I have a bunch of data which is assumed to be instances of a geometric random variable with outliers. How can I do a robust estimation of the parameter $p$ so that the effect of outliers is minimized?
As a part of the estimation process, I also need to know which are the outliers in the data.
I am looking for some solu... |
I've been using low discrepancy sequences for a while for Uniform Distributions, as I've found their properties useful (mainly in computer graphics for their random appearance and their ability to densely cover [0,1] in an incremental fashion).
For example, random values above, Halton sequence values below:
I was cons... |
I am want to assess whether successful implementation of newly developed policies are dependent on involvement of all relevant stakeholders and middle managers.
I have a 5-point Likert scale with ten questions (items). I collected data on 85 respondents. I assigned values ('Strongly Agree'=1, 'Agree'=2, 'Undecided'=3, ... |
I have some data and I want to build a model (say a linear regression model) out of this data. In a next step, I want to apply Leave-One-Out Cross-Validation (LOOCV) on the model so see how good it performs.
If I understood LOOCV right, I build a new model for each of my samples (the test set) using every sample except... |
I have quite a complicated data set to analyze, and I cant find a good solution for it.
Here is the thing:
1. the raw data is essentially insect song recordings. Each song is made of several bursts, and each burst made of sub-units. All individuals have been recorded for 5 minutes. The number of bursts and their posi... |
I have a set of 9 possible features that I can extract from an image. Does anyone know of a method that I can employ to utilize the best feature combination to get the maximum possible classification accuracy?
|
I'm not a statistician but I'm writing my thesis on mathematical finance and I think it would be neat to have a short section about independence of stock returns. I need to get better understanding about some assumptions (see below) and have a good book to cite.
I have a model for stock prices $S$ in which the daily (... |
I have data set of ints with values 1..10.
Before any sample is added to the dataset it can be observed for a period of time. During this period X can grow from 1 to 10 (Note : it only grows in one directio through all values 1,2,3...10).
Once added it cant change.
For example if you are observing next X currently be... |
Suppose I want to measure similarity between users. If two users match on an item that is very improbable, I want to give greater weight to that.
|
I recently studied two asymmetric t distribution both with a name of skewed-$t$. I am confused with their differences or are they actually the same?
The first one is introduced by Hansen (1994) with pdf:
$f(x;\nu,\zeta)=\begin{cases}
\begin{array}{cc}
bc\left(1+\frac{1}{\nu-2}\left(\frac{bx+a}{1-\zeta}\right)^{2}\rig... |
I'm looking for help in determining how to equate the following:
We have a surface of 13 cm X 10 cm.
We have a 95% probability of hit
on a 16 cm diameter surface.
I would like to equate $B$, probability of hit to the 13cm X 10 cm surface. 95% probability of hit on a circle of 16 cm represent what probability of hit ... |
I'm working on a "player phylogeny" to help make comparisons between potential NBA draft picks and current players. An example is shown below:
I'm using the dist() function in R, and am assuming that all factors are equally weighted. It's clear to me by looking at the results that some factors need to carry more weigh... |
I am in charge of quality control of n = 400 reports. Most of the quality checks are automated, but some have to be manual. I need to figure out how many reports my team needs to check manually in order to be fairly confident that all of the reports are error free in the areas which require manual checks. How can I ... |
I have a question (simpler than my previous post today I hope!), which is probably very stupid as nobody has never asked it before.
Lets say I am trying to explain the effect of 3 variables (A, B and C) on a dependent one (Y). Biologically speaking, A and B should really have an effect on Y. So I am testing:
Y ~ A + ... |
In short, is there anything to be learned from performing a Phi measurement of association (MOA) on a Chi-Square test where it failed to reject the null hypothesis?
$$\phi = \sqrt{\chi^2/N}$$
where $\chi^2$ is the value returned by Chi-Square and $N$ is the number of observations.
Or is the phi coefficient only useful ... |
One of the breakthroughs of econometrics over the past two decades has been to employ "clustering" to take into account the correlation of error terms across observations. For instance, if you're evaluating the effect of an educational intervention where you have data on individual students but you suspect that teacher... |
I'm using the geepack package in R to fit a variety of models to repeated measures data, albeit with varying cluster sizes. However, for some correlation structures ("exchangeable", for instance), I obtain unreasonably large estimates for my parameters, usually on the order of $10^{13}$ to $10^{16}$, with standard erro... |
I'm developing a forecasting model for an infectious disease for a hospital and wanting to understand if I should use disease counts or rates (based on population or total clinic visits). What are the implications of using one approach over another (besides practical considerations, such as having an accurate populatio... |
I've been very interested in data-mining and machine-learning for a while, partly because I majored in that area at school, but also because I am truly much more excited trying to solve problems that require a bit more thought than just programming knowledge and whose solution can have multiple forms. I don't have a re... |
Suppose you're renowned statistician down on his luck, for whatever reason, and only has $100 to live on for the next week.
Suppose next, someone offers you a game by flipping a coin (no gimmicks with coin) and offers to give you 150 dollars if it lands on heads and take your 100 dollars if it lands on tails (no food f... |
I was wondering what happens to bias and variance of GLM estimates as dimensionality approaches the number of training data points? Specifically in Linear Regression and Poisson Regression?
I know for Logistic Regression there is the Hauck-Donner phenomenon, which increases separation in the data, and increases the var... |
I understand that to calculate the probability of two independent events both happening, one can simply multiply the probabilities.
However, consider the following:
A list of counties in the East coastal U.S. Each county has a calculated probability of a hurricane making landfall next year. I am trying to calculate the... |
I am interested in non-parametric methods for building confidence intervals for an estimator (e.g. the mean) using few samples (e.g. 10). I think I have read somewhere that smoothing the bootstrapped estimator values can improve the quality of the derived percentiles interval. However I could not find any online refere... |
So, [Wikipedia says] that the standard definition of independence is:
$f_{X,Y}(x,y) = f_X(x) f_Y(y)$
How is this applied to timeseries? How do we calculate each side of the equation?
If we're assuming that the probability distributions of the two series are the same, then $X=Y$ and we can just use $f(x,y) = f(x) f(y)$... |
Possible Duplicate:
How do I reference a regression model's coefficient's standard errors?
If I have a dataset:
data = data.frame(xdata = 1:10,ydata = 6:15)
and I run a linear regression:
fit = lm(ydata~.,data = data)
out = summary(fit)
Call:
lm(formula = ydata ~ ., data = data)
Residuals:
Min 1Q ... |
A massive problem in communicating the results of statistical calculations to the media and to the public is how we communicate uncertainty. Certainly most mass media seems to like a hard and fast number, even though except in a relatively small number of cases, numbers always have some uncertainty.
So, how can we, as ... |
My background is in labor economics/applied micro but I am currently working with data collected from a field experiment. My experimental/micro skills are rusty to say the least.
In my data, I observe individuals choosing one of the choices $A, B, C, D$. The value of the choice is realized after the choice. I know that... |
First, I'm sorry for the long post, but I needed a second opinion from you, the experts, about this problem!
I was reading a paper by Gallagher (2006), where he puts an example on "how one may correctly perform an F-test and how some softwares perform poorly on this task" (which could have been a pretty interesting pa... |
I have a response variable(y) and 20 independent variables (Xs). I want to select several Xs in the linear regression, but I'm not sure how many variables should be selected. To select the best number of variables, I use the sum of the squared residuals (Res) in the 10-fold cross-validation given N selected variables (... |
On visual inspection of P-P plots, my time data appears to fit a Weibull distribution better than a normal distribution. I will use the variable for correlations and as a predictor in regression. In SPSS, I could fit the data to a Weibull regression model. I have also read that you can Vincentize the data, but I am unf... |
What follows is a theoretical power calculation for a practice exam, but this seems very low. Did I do something wrong? The problem and solution is as follows:
In a drinks factory the mean fill of the cans is set at 300 ml but there is a concern that the population mean fill of the cans may not in fact be 300 ml. Assu... |
Background
There is a lot of discussion around this, so I thought that I could find my answer from earlier treads on StackExchange and by googling furiously. After using half a day trying to find only one reference book for (bio)statistics with R, I got utterly confused and had to give up. Maybe the free material combi... |
Someone in my lab has a sample of 500 older kids and he wants to investigate what factors are related to the probability that they will bully. Groups:
bullied not
bully 22 28
don't 200 250
They created an interaction variable using age*not bullied/bullied and added 14 other "predictors" to th... |
I thought it had to do with varying numbers of factors but based on the literature I have read it seems to do more with fixing/freeing of parameters. Any info would be greatly appreciated!
|
I'm trying to do a pairwise test to calculate p-values between various products that are being evaluated by several assessors. I'm trying to reproduce what SAS is doing in R, and I'm running into an issue in one particular situation: when the items being compared (in my case SAMPLE) are complete for one item in the pa... |
Regarding regression analysis, I once heard that "Replicate at various predictor values will allow for lack-of-fit analysis". I do not understand how to get this kind of statement?
|
I have a feature vector containing 17 features. I need to take only features containing 98% variance. So I did principal component analysis (PCA) in Matlab like this:
[COEFF,SCORE,latent] = princomp(X);
cumsum(latent)./sum(latent)
and got this:
0.9082
0.9824
0.9999
0.9999
1.0000
1.0000
1.0... |
I am interested in training a simple binary linear classifier. That is, I will find a vector of weights $\bf w$ such that I can predict the class of new example by the sign of
$f(x) = w^T x$.
I will find the weights in the standard way, by minimizing the empirical risk of some loss function
$\sum_i L(w^T x^{(i)}, y^(i... |
I've written some Python code which does some (network) data analysis. It's mostly large data coming from SQL where I play around with statistics and algorithms.
However configuring the interplay between modules and tracking/debugging what's going on with the data isn't very convenient.
Do you know a tool which could n... |
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