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My supervisor asked me to find out which distribution represents a particular situation.
I have a VoIP generator that generates calls "uniformly" distributed between callers. This means that the volume per caller distribution is "almost" uniformly distributed between a minimum and maximum. So by running a test with 100... |
I want to graphically show the change in relative risk along with confidence limits over 17 years.
Can I use a forest plot without meta-analysis because it will have the added advantage to tabulate Z-values and p-values also? Here I want to show the progressive change in the relative risk and NOT meta-analysis.
Or is... |
Does $R^2 * \mbox{slope}$ provide an estimation of cause and effect? For example, if $R^2$ of miles driven and coffee consumed is $x\%$ and the slope of the coffee-and-miles dataset is $y$ (miles/coffee), can you say "$z$ of each cup of coffee drunk is related to the number of miles driven"?
|
The recent events in Japan have made me think about the following.
Nuclear Plants are usually designed to limit risk of serious accidents
to a 'design basis probability' for example, say, 10E-6/year.
This is the criteria for a single plant.
However, when there is a population of hundreds of reactors, how do we combine ... |
I am a senior doing a science fair project on the efficiency of fuels. For each fuel I tested, I have a time series of temperature.
I want to plot these into an excel xy chart, how do I plot them if the constants (time) are not the same for each set of data?
|
I recently was asked to help characterize some surfaces (raised ink dots on paper) that were scanned with a profilometer, yielding height data across a grid of x & y coordinates. The critical question was to characterize the average dot height. The data were rather noisy as the paper was not perfectly flat, so I played... |
We're creating a chart showing traffic by time of day over a given period. So the y-axis is traffic, the x-axis is midnight, 1am, 2am, etc. It could also be days of the week. What's the generic name for this type of chart? I've come up with "cycle chart". Is that the standard? Is there one?
Update:
Just to add a bit m... |
We know that density for a student-t distribution is given as
$$\frac{\Gamma(\frac{\nu + 1}{2})}{\Gamma(\frac{\nu}{2})} \left(\frac{\lambda}{\pi\nu}\right)^{\frac{1}{2}} \left[1+\frac{\lambda(x-\mu)^2}{\nu}\right]^{-\frac{\nu+1}{2}}$$
with
$\text{E}(X) = \mu$,
$\text{var}(X) = \frac{1}{\lambda}\frac{\nu}{\nu-2}$
wher... |
Let's say I'm performing regularized regression and I want to validate the results using holdout. (I'm choosing holdout instead of cross-validation because my dataset is fairly large, so computational power is an issue and the difference between holdout and cross-validation estimates will likely be negligible.) I wan... |
I'm working on a naive Bayes classifier that calculates probabilities using a normal Gaussian distribution. This works very well when I am classifying something into two mutually exclusive buckets (e.g. spam vs. not-spam), but when I am working with a factor that is not easily classified that way (when the classificati... |
In network motif algorithms, it seems quite common to return both a p-value and a Z-score for a statistic: "Input network contains X copies of subgraph G". A subgraph is deemed a motif if it satisfies
p-value < A,
Z-score > B and
X > C,
for some user-defined (or community-defined) A, B and C.
This motivates the ques... |
I am reading Stephen Taylor's Asset Dynamics book and came across something I didn't fully understand.
For an ARCH process, the return series is modeled as
$r_t = \mu_t + h_t^{1/2}z_t$ where is $z_t$ is $D(0,1)$ and may be normal/non-normal and $h_t$ is conditional variance (some function of subset of $\theta$).
Then h... |
I am researching age at first sexual debut and HIV prevalence in Lesotho. I want to analyse the data using logistic regression with SPSS. My variables are age, sex, social status, education level, and environment. How am I to allocate my variables?
|
I want to learn how Gibbs Sampling works and I am looking for a good basic to intermediate paper. I have a computer science background and basic statistic knowledge.
Anyone has read good material around? where did you learn it?
|
I want to compare the slopes of progression of a variable that is measured in percentage versus a variable that is measured in decibels. What is a good method to compare?
|
I've calculated Cohen's d for regression coefficients (from the t statistic), odds ratios and means differences, hoping to pool the results in a meta-analysis and see how it works. However, in Stata, it doesn't seem you're able to pool these results without confidence intervals for Cohen's d, so my question is how do I... |
I'm trying to make sense of some data and get statistical results on them.
What I have is the following:
Subject TimeOfDay Test1 Test2 Test3
A 10:00 valA1 valA2 valA3
B 10:00 valB1 valB2 valB3
C 15:00 valC1 valC2 valC3
D 15:00 ... |
I'm using the following function to calculate Edwards R^2 (formula 19 in Edwards et al. 2008) of a mixed effects model (I hope the implementation is correct):
r2lmer <- function(model) {
require(aod) # need the aod package for wald.test function
if (class(model) != "mer") stop("mer object expected")
n <- model... |
I have two sets of coefficients from similar data taken at different times. What I want to do is combine the two sets of coefficients giving greater weight to the more most recent set.
The goal is building a predictive model. So say I have dataset A from 2009, and dataset B from 2010.
My coefficients for A are:
param... |
car packages's ellipse function asks for a radius parameter. In help says that is the "radius of circle generating the ellipse". Could you please tell me which circle is this?
Thank you very much
|
A Poisson regression is a GLM with a log-link function.
An alternative way to model non-normally distributed count data is to preprocess by taking the log (or rather, log(1+count) to handle 0's). If you do a least-squares regression on log-count responses, is that related to a Poisson regression? Can it handle simila... |
Christopher Manning's writeup on logistic regression in R shows a logistic regression in R as follows:
ced.logr <- glm(ced.del ~ cat + follows + factor(class),
family=binomial)
Some output:
> summary(ced.logr)
Call:
glm(formula = ced.del ~ cat + follows + factor(class),
family = binomial("logit"))
Deviance Resi... |
Suppose I have some stochastic process $X_t$. At each time $t$, I receive an estimated probability distribution for $x_t$, followed by an observation $x_t$. After receiving a set of observations ${x_1, \ldots, x_n}$, I want to go back and re-estimate the probability distribution for each $x_t$, $1 \le t \le n$. What ar... |
Let's say $y$ is a linear function of $x$ and a dummy $d$. My hypothesis is that $d$ itself is like a hedonistic index of a vector of other variables, $Z$. I have support for this in a $MANOVA$ of $Z$ (i.e. $z_1$, $z_2$, ..., $z_n$) on $d$. Is there any way to test the equivalence of these two models:
Model 1: $y = b_0... |
I am by no means good in statistics, but I think I have come to the right place.
My question is simple:
My problem consists of comparing the population of several states in a small country, but some states have a population of 3000,000 and some a population of 2,000.
I am painting it on a map, and the "intensity" of th... |
Positive stable distributions are described by four parameters: the skewness parameter $\beta\in[-1,1]$, the scale parameter $\sigma>0$, the location parameter $\mu\in(-\infty,\infty)$, and the so-called index parameter $\alpha\in(0,2]$. When $\beta$ is zero the distribution is symmetric around $\mu$, when it is positi... |
I have a set of systems where uncertainties accumulate within it. These aren't always purely additive - sometimes they are, sometimes they aren't. I've had some success in using fan-charts, bar charts with confidence-intervals, and box plots for communicating single items.
But how can I show how uncertainties accumulat... |
We're thinking of adding an interactive near real-time analytics functionality (a-la "Google Analytics") to a product Movie Recommender Engine.
We need to let the user interactively create analyses deciding on a case by case basis the analysis dimensions (e.g. by Genre, by Actor, by Publisher), metrics (e.g. Views, Pur... |
Here's what I know:
I have read the chapter (p347ff) in Agresti, 1990, regarding dependent two-way tables, and I believe I understand the basics. My problem is that Agresti's model-based approaches seem to rely on large-sample theory.
I have questions from 24 students where they rate something on a scale from 1-5. If ... |
I have a rather basic question about Probabilistic Principal Component Analysis, which I am now trying to apply to a real-world problem.
In PPCA, the crucial assumption is that the generating process of the observations in $R^n$ is $t=Wx +\sigma^2\epsilon$, where x are iid standard gaussians in $R^q$ (with $q \le n$) ... |
First of all I'd like to apologize for the vague title, I couldn't really formulate a better one just now, please feel free to change, or advice me to change, the title to make it better fit the core of the question.
Now about the question itself, I have been working on a software in which I have come across the idea o... |
I've been trying to get my hands on a substantial resource for using Gibbs sampling in hybrid Bayesian networks, that is, networks with both continuous and discrete variables.
So far I can't say I have succeeded. I'm interested in hybrid networks where there are no constraints regarding discrete children having contin... |
I have some problems in using (and finding) the Chow test for structural breaks in a regression analysis using R. I want to find out if there are some structural changes including another variable (represents 3 spatial subregions).
Namely, is the regression with the subregions better than the overall model. Therefore I... |
What do you call a curve that is just the first half of a bell curve. For example, let's say in a typical bell curve of letter grades, a few students get F grades most get C grades and just a few get A grades.
I'd like a curve that is the first half of the bell curve so that a few students get F grades and the most co... |
The whole point of AIC or any other information criterion is that less is better. So if I have two models M1: y = a0 + XA + e and M2: y = b0 + ZB + u, and if the AIC of the first (A1) is less than that of the second (A2), then M1 has a better fit from the information theory standpoint. But is there any cutoff benchmark... |
Related to my previous question, I have a dataset of 2D points with an associated label (this label can take 6 different values). As suggested in the answers to my other question, this can be modeled as a marked point process (or 6 different point processes), allowing to apply standard tools to study this dataset.
I wo... |
I wonder if it possible to include a mediation effect in multinomial logistic regression. I have a categorical (3 categories) outcome variable and four predictors (all continuous). I expect one of the predictors (X1) to mediate the relationship between the outcome variable and another predictor (X2). I also expect dire... |
I have a completely within-subjects design with 3 independent variables:
Trial type (3 levels)
Task order (2 levels)
Modality (3 levels)
However, for one of my levels of Trial type, the Task order and Modality levels are redundant (because it is essentially a baseline measurement).
Ideally, I'd like to run a 3 (trial... |
Actually this question may be simple for you, but I need to learn the correct answer.
If I remove misclassified instances from data set with Naive Bayes (it gives minimum FP rate) and then train logistic classifier on this filtered data set, will it overfit or not?
Thanks in advance.
|
I am trying to use DLM to model a time series. Candiate model includes local level, local trend and local trend with seasonal part. I do not know how to do model selection. Can AIC be calculated? I found no function in the R package dlm.
|
The research group I work for have developed a theoretical growth model for a particular species of fish. The idea is that if you provide some initial starting values for the model you then generate an expected growth curve along with 95% confidence bands. To extend the model we would like to be able to update the mode... |
I am trying to test importance sampling for a simple a Wiener process $W_t$ in R:
set.seed(123)
Z <- matrix(rnorm(12*1000),12,1000)
W <- apply(Z,2,cumsum) #Wiener process simulated 1000 times for 12 periods
B <- W-(1:12) #Brownian motion with drift -1
w <- exp(-W[12,]) #Radon-Nikodym derivative (actually w <- exp(-W[12... |
I'm looking for a solid reference (or references) on numerical optimization techniques aimed at statisticians, that is, it would apply these methods to some standard inferential problems (eg MAP/MLE in common models). Things like gradient descent (straight and stochastic), EM and its spinoffs/generalizations, simulated... |
I know a fair amount about fitting continuous parameters particularly gradient-based methods, but not much about fitting discrete parameters.
What are commonly used MCMC algorithms/techniques for fitting discrete parameters? Are there algorithms which are both fairly general and fairly powerful? Are there algorithms w... |
Probability distribution of two classes is given by $N(5,1)$ and $N(6,1)$ where
$N(\mu,\sigma^2)$:
$$f(x) = \frac{1}{\sqrt{2\pi \sigma^2}} e^{-\frac{(x-\mu)^2}{2\sigma^2}} $$
How to classify them, and see error rate?
I am doing this in MATLAB
Taking 500 samples of each distribution and tagging them depending where ... |
Context:
I'm a Psychology PhD student. As with many psychology PhD students, I know how to perform various statistical analyses using statistical software, up to techniques such as PCA, classification trees, and cluster analysis.
But it's not really satisfying because though I can explain why I did an analysis and what... |
I have conducted an analysis in which I have modeled different variance components. When reporting the results in a table, it is much more concise to report standard deviations instead of variances.
So, this brings me to the question - is there ever a reason to report variance instead of standard deviation? Is it ever ... |
I have a few hundred estimates of a parameter calculated from two different models and I would like to know if these parameters have different variances.
What is a straightforward test for comparing the variances of these parameters? (straightforward meaning, least assumptions).
|
I come from the social sciences, where p < 0.05 is pretty much the norm, with p < 0.1 and p < 0.01 also showing up, but I was wondering: what fields of study, if any, use lower p-values as a common standard?
|
How do probability distributions of continuous random variables transform under functions?
I.e. I have a random variable, X, drawn from a normal distribution with mean 0 and variance 1. What is the probability distribution associated with sin(X)?
More generally, what are the rules for transforming continuous random va... |
I'm working on a problem as follows for a course that I'm auditing:
Suppose a 95% symmetric t-interval is applied to estimate a mean, but the
sample data are non-normal. Then the probability that the confidence interval covers
the mean is not necessarily equal to 0.95.
Use a Monte Carlo experiment to
estimate ... |
I admit I'm relatively new to propensity scores and causal analysis.
One thing that's not obvious to me as a newcomer is how the "balancing" using propensity scores is mathematically different from what happens when we add covariates in a regression? What's different about the operation, and why is it (or is it) better... |
I would like to perform column-wise normalization of a matrix in R. Given a matrix m, I want to normalize each column by dividing each element by the sum of the column. One (hackish) way to do this is as follows:
m / t(replicate(nrow(m), colSums(m)))
Is there a more succinct/elegant/efficient way to achieve the same t... |
I am working on a stopping rule for an optimization algorithm that produces an upper bound and lower bound for the objective value of an optimization problem. In my case, the lower bound is deterministic, but the upper bound is an estimate derived from $N$ data points $UB_1, UB_2... UB_N$ with mean $\widehat{UB}$ and s... |
I am reading this example, but could you explain a little more. I don't get the part where it says "then we Normalize"... I know
P(sun) * P(F=bad|sun) = 0.7*0.2 = 0.14
P(rain)* P(F=bad|rain) = 0.3*0.9 = 0.27
But where do they get
W P(W | F=bad)
-----------------
sun 0.34
rain 0.66
Example from
|
I have two different columns of data which are recorded in different configurations and I want to show the users that these two records varie (data is time in seconds). The dataset is not of the same size as shown below. The end users are all experienced people in stats and math. My question is how can I plot a graph ... |
I am trying to determine if a given noise from a compass sensor is time-correlated (it is supposed to be!) and for that I tried to compute the cross correlation between the noise signal and the time of sampling using Matlab xcorr() function. However, I am getting a random value indicating that it is not time-correlated... |
An increase in the number of cases and deaths occurs during epidemics (sudden increase in numbers) due to a virus circulation (like West Nile Virus in USA in 2002) or decreasing resistance of people or contamination of food or water or increase in the number of mosquitoes.
These epidemics will present as outliers whic... |
I was fiddling with PCA and LDA methods and I am stuck at a point, I have a feeling that it is so simple that I can't see it.
Within-class ($S_W$) and between-class ($S_B$) scatter matrices are defined as:
$$
S_W = \sum_{i=1}^C\sum_{t=1}^N(x_t^i - \mu_i)(x_t^i - \mu_i)^T
$$
$$
S_B = \sum_{i=1}^CN(\mu_i-\mu)(\mu_i-\mu)^... |
I have carried out a principal components analysis of six variables $A$, $B$, $C$, $D$, $E$ and $F$. If I understand correctly, unrotated PC1 tells me what linear combination of these variables describes/explains the most variance in the data and PC2 tells me what linear combination of these variables describes the nex... |
I want to understand how to make calculations on the prevalence of a disease in a country population and the impact that the element of average life expectancy (of those suffering with the disease at time of diagnosis) has on this calculation.
Are there any 'best practice' papers on making epidemiology calculations?
|
The ISO VIM defines them as:
measurement method:
generic description of a logical organization of operations used in a
measurement.
measurement procedure: detailed description of a measurement according to one or more measurement principles and to a given measurement method, based on a measurement model and includ... |
If I find that my covariate (reaction time) alters over the length of my experiment (e.g. due to fatigue), can I somehow build that into my model?
So what I am saying is that the effect of my covariate is not constant (between subjects and within subjects).
|
Given two bivariate normal distributions $P \equiv \mathcal{N}(\mu_p, \Sigma_p)$ and $Q \equiv \mathcal{N}(\mu_q, \Sigma_q)$, I am trying to calculate the Jensen-Shannon divergence between them, defined (for the discrete case) as:
$JSD(P\|Q) = \frac{1}{2} (KLD(P\|M)+ KLD(Q\|M))$
where $KLD$ is the Kullback-Leibler... |
Greetings,
Is it possible to use evidence in a Winbug model? For example, a random variable in a model has been observed, and I'd like to update the other variables in the model, pretty much the same update perfomed in tools like Smile, or other inference software.
Gibbs sampling is supposed to use observed values in... |
I want to perform a single-tail test on a single sample of real numbers (N~100) against an expected value. The population is known to be not normally distributed. So from what I've read about stats, I can do my testing using
Wilcoxon signed rank test, or
bootstrap shifted sample data to obtain the null distribution ... |
I'm using a tutorial I found and plotting mean values along with the standard errors to show my data. But I'm having a problem discussing the results. My plot is as shown below: some of the standard errors (shown as a error bar) vary much and some of them are very close to zero.
|
Is there a way to find the Spearman correlation between two Weibull distributions? I need it as a parameter in a copula function for the joint Weibull distribution.
I learned that using the Pearson correlation, which I can easily obtain from the variances and cross variances of the given spectra, is not reliable with c... |
I am interested in estimating how many subjects should be included in a brain imaging study. Although the design is a fairly straight forward cross-sectional comparison, there are a number of tweakable image processing steps between the raw image and the processed image in which we carry out pixel-wise comparisons.
I'v... |
which is the % of population with vote rights(above 18yo for example). Can u point me to some papers which talks about voting and ages?
|
I'm trying to undertake a logistic regression analysis in R. I have attended courses covering this material using STATA. I am finding it very difficult to replicate functionality in R. Is it mature in this area? There seems to be little documentation or guidance available. Producing odds ratio output seems to require i... |
I have the sample population of a certain signal's registered amplitude maxima. Population is about 15 million samples. I produced a histogram of the population, but cannot guess the distribution with such a histogram.
EDIT1: File with raw sample values is here: raw data
Can anyone help estimate the distribution with t... |
I used summary.formula from Hmisc with continuous Age and binary outcome O with test=TRUE. This returned a p-value for Age predicting O (if I understand this correctly).
I then ran a glm using Age and O (univariate logistic regression), which returned a different p-value. I thought that the p-value should be the same... |
I want to carry out a power analysis on a one group repeated measures experiment using G*power.
I have a group of subjects who tested a set of products. Each subject test one time the products. Hence, I have one observation per cell.
To test the product effect, I used a two anova model with subjects as random effect ... |
I currently have two sets of input variables say, $X$ and $Y$ with one output variable $Z$. That is:
$$Z = a_0 + a_1X_1 + a_2X_2... + a_{11}X_{11} = b_0 + b_1Y_1 + b_2Y_2 + b_3Y_3 + b_4Y_4$$
I have the independent $X$ and $Y$ values but don't have the dependent variable $Z$ values.
Is there anyway that I can estimate c... |
I just came by a post talking about networks for displaying correlations:
Is this a known method? Can someone shed some insights into it? (I'm wondering about how useful it might be, and when.)
|
In R, if I write
lm(a ~ b + c + b*c)
would this still be a linear regression?
How to do other kinds of regression in R? I would appreciate any recommendation for textbooks or tutorials?
|
Suppose I wanted to fit a model of the form
$$y_i = \beta_0 + \sum_{1 \le j \le k} \beta_j X_{i,j} + \gamma_i Z_i + \epsilon_i,$$
to some data, where the regressors $X$ and $Z$, and the regressand $y$ are observed, and where $\gamma_i$ is a Bernoulli random variable that equals one with (unknown) probability $p$ and is... |
I'm comparing scores for two small groups of individuals that competed in a tournament, and I'm being told that the comparison calls for a Mann-Whitney U test. It feels wrong to me, though: my two sets of scores are fundamentally interdependent because the two groups competed against one another.
Briefly: I have two gr... |
I want to transpose a data frame in R with unstack. Consider the two data frames, a and b:
> a
count state
1 199665 RSTO
2 4147 RSTR
3 31274 S1
4 1 S2
5 2522 S3
6 118009 SF
> b
count state
1 31956 RSTO
2 11689 RSTR
3 6702 S1
4 2838 S2
5 6268 S3
6 672561 SF
My problem... |
I have some issues with an exploratory factor analysis.
Can anybody please tell me how to calculate the Average Variance Extracted (AVE) and the Composite Reliability from two factors, each with three items using SPSS? If not with SPSS, Stata might help too.
|
UPDATE: caret now uses foreach internally, so this question is no longer really relevant. If you can register a working parallel backend for foreach, caret will use it.
I have the caret package for R, and I'm interesting in using the train function to cross-validate my models. However, I want to speed things up, and... |
I am examining the difference between a physical feature of different species of animals. Due to the nature of my experiments I'm using a nonlinear mixed model with the following setup:
lme(log10(feature) ~ log10(Body.mass) + factor(Trial.Number), random = ~1 | IndividualID, data=animals, subset=Frfactor=="low", na.act... |
The title defines the question. May be the concept would do...like how to go about it? Thanks.
|
I have 2 alternative methods to solve a problem, and I was just wondering what people who know the math better than I think, and if there is a better method to use for this type of problem.
The problem: I have a list of lat/lon positions and a value for the time interval between position updates and wish to find the SO... |
Is it possible to perform logarithmic regression on multiple variables with Excel? If I just have a single independent variable than it's very easy to do this using the best-fit line option (it lets me switch from linear to logarithmic). But this feature does not work for multiple variable regression and the regression... |
I have a basket of time series (stock prices). I want to find the N (fixed or not) time series that will best replicate the basket in the sense that combination of them will be best cointegrated with the basket.
Beside using the N series that have the best cointegration scores (ADF test) and regressing these variables ... |
Let $X_1, X_2, ..., X_n$ be a random sample from a distribution with p.d.f.,
$$f(x;\theta)=\theta^2xe^{-x\theta} ; 0<x<\infty, \theta>0$$ Obtain minimum variance unbiased estimator of $\theta$ and examine whether it is attained?
MY WORK:
Using MLE i have found the estimator for $\theta=\frac{2}{\bar{x}}$
Or as $$X\sim ... |
I've developed a logit model to be applied to six different sets of cross-sectional data. What I'm trying to uncover is whether there are changes in the substantive effect of a given independent variable (IV) on the dependent variable (DV) controlling for other explanations at different times and across time.
My questi... |
I have a database with many attributes. I would like to know which attributes has the minimum variation in the data. Is there some standard technique? It should be like clustering without split records in clusters. I would like to know what the records in particular cluster have in common.
I was going to compute the m... |
I tried to use the Kernel Density plot method from Hayfield and Racine (2008) np package for my own data, but somehow ended up with different type of plots and I have no idea what the difference is between my data and the example data provided by the package.
I used the Italy GDP example that is provided in the np pac... |
I'm trying to gain a better understanding of kmeans clustering and am still unclear about colinearity and scaling of data. To explore colinearity, I made a plot of all five variables that I am considering shown in the figure below, along with a correlation calculation.
I started off with a larger number of parameters,... |
I am new to time series analysis, and would appreciate any suggestions on how best to approach the following time-series regression problem: I have hourly temperature measurements at approximately 20 locations across one site over three years, along with static ancillary information (slope, elevation, aspect, canopy co... |
Most repeated measures ANOVAs have time as the repeated measure; I was wondering about using a repeated measure that is not time.
Say we fed two groups of animals different diets. At the end of the experiment, we sample the tissues, and measure ~30 different compounds (e.g. different fatty acids [FA]). Animals are sam... |
Is there a well founded rule for the number of significant figures to publish?
Here are some specific examples / questions:
Is there any way to relate the number of significant figures to the coefficient of variation? For example, if the estimate is 12.3 and the CV is 50%, does that mean that the information represen... |
It's pretty tough to search the Web for info on something when you don't know what words are commonly used to describe it. In this case, I'm wondering what it's called when you include another predictor in a time series.
As an example, say I'm modeling a variable $X$ using AR(3):
$ X_t = \varphi_1 X_{t-1} + \varphi_2 X... |
There is a bayesian network Asia:
I am computing based on
A (visit to Asia)
S (smoker)
T (tuberculosis)
L (lung cancer)
B (bronchitis)
E (tuberculosis versus lung cancer/bronchitis)
D (dyspnoea)
X (chest X-ray)
P(A)=0.01
P(S)=0.50
P(T)=0.0104
P(L)=0.055
P(B)=0.45
P(E)=0.064828
P(D)=0.4393105
P(X)=0.11029004
Ho... |
I have some points $X=\{x_1,...,x_n\}$ in $R^p$, and I want to cluster the points so that:
Each cluster contains an equal number of elements of $X$. (Assume that the number of clusters divides $n$.)
Each cluster is "spatially cohesive" in some sense, like the clusters from $k$-means.
It's easy to think of a lot of cl... |
I am working on something to test advertisements. I have 3 independent variables I want to test (with mixed numbers of variations of each variable), and I would like to find the best combination of the three by looking at their effect on a single dependent variable (the percentage who purchase).
TITLE IMAGE DESCR... |
I am working in hospital processing infection data, and start to read more and more articles on regressions and statistics, having realized that my mathematics background is not sufficient for me to handle all the maths inside the article. I plan to do some self-study.
I have seen from here that calculus and linear alg... |
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