All Questions

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Mean and Standard deviation

The filling machine used by a dairy company to fill 1kg containers of yoghurt produces output which follows a normal distribution with mean 1030g (slightly more than 1kg) and standard deviation 20g. ...
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Negative binomial mixed effect model for repeated measures with R - prediction and plotting

I have a dataset to analyze in which a response was recorded at the ends of months 1,3,4,5,6 in 187 patients. All patients had the responses recorded in each week, and all patients started a treatment ...
5 views

Performing t test, one-way ANOVA from mean and SD using SPSS

I have the following summarized data: Group 1: n=44, mean 12.1, SD 2.0 Group 2: n=56, mean 13.2, SD 2.5 Group 3: n=42, mean 12.7, SD 2.3 Is it possible to perform the t test comparing means of group ...
5 views

Interpretation of variance component

In a report, I came across the following table and unfortunately there is no description for it. I have very limited knowledge of statistics. Could someone kindly let me know what the interpretation ...
8 views

What is the area under the normal curve that describes the probability that more that 43 households have a gas stove

HW 7.4 random variable will be approximated using the normal distribution
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Random Coefficient Negative Binomial Model

I have a crash count data and i want to build a random coefficient negative binomial model in R. The dependent variable will be the crash counts and covariates will be Lane width, AADT, shoulder width ...
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What does it mean for a function to be “contained in” a confidence band?

So I have this problem that asks me to generate 100 random samples from a standard normal, and I did. It asked me to find a 95% confidence band and I did, using the Python code ...
2 views

Jackknife estimator for coefficient of variation

I have one of the estimator of coefficient of variation and i am using jackknife method to reduce bias. I am running R code to do the simulation for this study. The result i am getting is not what i ...
12 views

Getting the Estimate of ref Level in Multiple Regression with Dummy Variable in R

I have this regression model in R using dummy variables ...
13 views

Locally weighted regression VS kernel linear regression?

I am trying to make it clear the relationship of the listed three methods. According to my understanding kernel regression means : the weight vector W lies in the space spanned by training data.  ...
10 views

What are the odds of having the same Lawyer make a mistake in two wills involving the same person? [on hold]

A lawyer made mistakes in my will and were caught while I was alive to have it fixed and then a loved one died and it turns out the very same lawyer made a mistake in his will that the deceased can't ...
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Why do we take the absolute value of weight of evidence when computing the information value?

I was looking at the explanation for Information Value calculation in STATISTICA and I find it a bit confusing: ...
8 views

Can I use deviance to compare the fit of a model to different datasets?

I'm using R's nls to fit different datasets to the same model. I've read that using R-squared is usually not correct for ...
10 views

What are the odds of having a 2 windows shot- one facing the west one year and another structure window the following? [on hold]

It is a small rural community with fields between our house and a hedgerow between us and the neighbors to the north, and different neighbors across the street with a field. It was always assumed ...
10 views

Forecasting daily visits using arima and external regressors

I have daily visitors data for last 10 years, i want to do some basic tests like which is the busiest day , which is the busiest month, busiest week etc.i used auto.arima and xreg function to find out ...
10 views

Forward sequential feature selection improving classifier performance?

I was in a bit of a conversation with a co-worker about using forward selection. My training data is on order of ~6,000 w/ dimensionality of 1,200, and testing data on order of ~3,000. Currently, I'm ...
32 views

Height of a normal distribution bell curve

For a normal distribution bell-shaped curve, one would have thought that the height should have an ideal value. Knowing this value may be one quick indicator to check if the data is normally ...
4 views

How does pruning and joining work in SPADE

How can we generate frequent item sets from a sequential data using CSPADE algorithm? How does pruning and joining work in this algorithm? I am new to data mining So, request to explain clearly from ...
9 views

How does the “summary” function that is run on a principal fitted components function work?

I'm playing around with the ldr package in R, which comes with Big Mac data. If I run this code (which is similar to one of the examples): ...
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Matching two populations that have different disease status that have undergone the same intervention?

If there are two populations, D+ and D-, where D is disease state, and both populations have undergone an intervention I, what would be the best way to design that study? Given that this is ...
18 views

Fitting an envelope to x-y data in R

I have some data that I'd like to create an envelope for it. As in the picture, the data is always positive and I'm looking for something that will capture my crudely hand drawn red line. It should ...
9 views

Correction of data using a correlation

Suppose I have measured the outcome variable A using a (psychophysical) test that determines the ability of a subject to discriminate between two stimuli with a certain difference (the variable X). It ...
4 views

When testing autoregressive conditional heteroskedasticity with GARCH do you need to include the ind. variables?

I have seen GARCH specified both ways... including the independent variables and excluding them. In the latter, only the ARCH and GARCH term remain in the specified regression equation. For testing ...
14 views

box-cox transformation altered my anova result

I have a non normal data and because of that i have decided to transform that data using Box-cox transformation. Even though the transformation worked really well, it changed my anova result. Here ...
6 views

What is obtained from the product of a probability and a log probability ratio?

I'm looking at the commonly used artificial neural network model that has nodes and connections. Quick refresher A connection has a source and target node, and a weight. The output of the source ...
10 views

Different variance estimator for multilevel ordinal logistic regression in Stata and R

I estimate a multilevel ordinal logistic regression models in Stata and R, and receive different estimators for the variance and the covariance of the latent variable of the higher level. Among other ...
3 views

Multilevel model with multiple level 2 variables

I am estimating a model with performance as the outcome, three level 1 predictors (age, sex, race) and three level 2 predictors (SchPopulation, SchSize, TeachingHrs). Level 2 predictors are the same ...
6 views

Calculating Marginal Data Density for VAR Model

I am currently estimating Bayesian vector autoregressive (BVAR) models and I would like to do model comparison with Bayes factors. I have read about the Gelfand-Day method, the Geweke (1999) modified ...
4 views

Significance test likelihood to detect a mean difference, and sufficient power

Here is my question: I need help on part D. This is my answer but I think it's wrong. Any suggestions are very appreciated.
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Any reason to report a Chi Square Test of Independence on a 2×2 table when I'm already reporting a 95% CI on the odds ratio?

I'm analyzing a 2×2 contingency table, and am going to a report a 95% CI on the Odds Ratio. Is there any point in prefacing this with a Chi Square Test of Independence? I understand that if the Odds ...
11 views

Piecewise-constant density estimation

I came across the term "piecewise-constant density estimation" in a paper and haven't been able to find a definition for it online or in my textbook resources. No example was given in the paper ...
9 views

R and fisher test in each row in a data frame [on hold]

![enter image description here][1] I basically have this dataframe and I would like to do a fisher test on it to see which of thoses elements are present more ...
5 views

How can i combine the three variables into one single measure in SPSS? [on hold]

How can i combine the three items into one single measure that indicates whether the respondent has taken part in at least one of the three activities treating it as a single dimension repertoire ? ...
11 views

How to specify reference category for binary independent variables in multinomial logistic regression in SPSS

I am using multinomial logistic regression in SPSS 20, with a DV with three ordinal categories, the last specified as the reference category. I have a mix of binary and ordinal IVs. I have no trouble ...
9 views

skip -9999 and perform multiple regression [on hold]

I want to do the multiple regression where SMDI is my dependent variable and other are my independent variable. I have following dataset to do the multiple regression: SMDI ET PRCP ET_Ch ...
20 views

Is the bias of a coin a latent variable or a parameter?

Consider the standard Bayesian estimation problem in which the bias $p$ of a coin is picked uniformly at random from $[0, 1]$, the coin is tossed a few times, and $p$ is then estimated from the ...
17 views

SAS NLMIXED proc and LOGISTIC proc results different

Consider a dataset $Z$ with $S\in \{0,1\}$ as binary response variable and 2 predictors $\{x_1, x_2\}$. ...
15 views

Is it ok to have a unit root within an independent variable?

The Dickey-Fuller and ADF tests testing for a unit root in variables are very sensitive. Some econometricians have personally indicated to me that in some cases it may be acceptable to model a ...
24 views

Kernel methods in machine learning?

I am beginning to tackle geostatistics problems where I tried to apply kriging(gaussian processes) to interpolate demographical water drop. According to my understanding, kernel methods are something ...
2 views

Influence function for inequality index using ordinal data

I wonder whether it is possible to derive influence function (explained for example here: Influence functions and OLS) for an inequality index designed for ordinal (non-continuous) data in this ...
4 views

nntool data normalizing [on hold]

I have some concerns related to the use of nntool in MATLAB toolbox. I have found that nntool by default normalizes the inputs to the range [-1 1]. how to changes these values both input and output ...
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deseasonalizing multiple series (more than 200 variables)

I'm trying to produce deseasonalization for multiple series using x-12 ARIMA (as an alternative, if you can manage, you also could provide an idea with other methods, such as x-13 ARIMA). The thing is ...
6 views

generating a sequence of indicators based on variable boundaries in JAGS

Suppose I have a vector of indices 1:N, and data y[1], ..., y[N]. I have three variable center points in ...
21 views

PDF and return on stock [on hold]

i thought the answer is just 1 -P(x=<15) = 0.5 (1dp) http://i612.photobucket.com/albums/tt201/Ivanreyes/Screen%20Shot%202015-03-27%20at%206.33.13%20am.png
118 views

Jelly Donut Puzzle - What Can Statistics Say About These Donuts [on hold]

I give you a box of 12 donuts. You randomly remove 5. They are all jelly donuts. What is the probability that there is another jelly donut in the box?
17 views

Equation in light of a given variance [on hold]

The total profit of a firm is given by Profit = Total Revenue – Total Cost Suppose that Total Revenue = 120Q and Total Cost = 20 + 50Q where Q, the quantity sold, is a (approximately) normal random ...