0
votes
0answers
2 views

Lagrange-Multiplier test for Serial Correlation

When testing whether $\epsilon_t$ is serially correlated in: $$y_t = \alpha + \beta_1x_{1t} + \ . . . \ + \beta_kx_{kt} + \epsilon_t $$ Can we simply test: $H_0: p = 0$ in the following: $$y_t = ...
0
votes
0answers
2 views

What kind of test should I do and how many participants do I need for this?

I am designing new functionality in a web application, and I am testing two variations on the navigation to attempt to determine which approach is more successful for our users. I am running the test ...
0
votes
0answers
7 views

How does Factor analysis explain the covariance and PCA explains the variance?

As I read in Bishop's PRML (here is the clip of that part about FA): According to the highlighted part, factor analysis captures the covariance between variables in the matrix $W$. I wonder HOW? ...
0
votes
0answers
4 views

Linear correlation in ANCOVA - necessary?

I've been told by my stats prof that running an ANCOVA relies on a series of assumptions, including that the the dependent variable and the covariate are linearly related. So, in SPSS the first thing ...
0
votes
1answer
6 views

analysing difference in variability between multiple related time series

I have constant time series (yearly from 1950 to 2010) of the abundance of several species that were captured by different groups. These series are somewhat related because the quantity of all species ...
0
votes
0answers
2 views

When is Micro-average Precision = Micro-average Recall

This page describes briefly on micro and macro precision used in computational evaluation: http://rushdishams.blogspot.de/2011/08/micro-and-macro-average-of-precision.html This paper surveys the ...
0
votes
0answers
5 views

Discriminant analyses with NIRS in R

I am working with a NIR matrix consistent of 134 rows (samples) and 1529 columns (wavelengths), from which I want to discriminate between two categories (species). I have successfully used the plsda ...
0
votes
0answers
7 views

Should I be using a GLMM?

I'm looking at the influence of pollen type on whether a flower sets fruit (i.e., yes or no = 1 or 0). Then looking at number of seeds per fruit (1-6 possible). I was told I should use lmer, however ...
2
votes
0answers
7 views

prediction from incomplete observations

Suppose I have a linear model predicting class-membership from a set of predictors. Now, I am going to classify a new observation which has, however, some predictor values missing. How can I deal with ...
0
votes
0answers
8 views

Linear model in R - 2 fixed and one random factor

I have performed an experiment on plants and have some trouble analysing the data. For the experiment, we have three replicates (in time), two species and three treatments. In each experiment, we ...
0
votes
0answers
5 views

Replicator Neural Network, Step-wise function causing same prediction

In my project, one of my objectives is to find outliers in aeronautical engine data and chose to use the Replicator Neural Network to do so and read the following report on it ...
2
votes
1answer
26 views

Does it make sense to impute year of birth?

This is data cleaning and preparation stage question for me. I apologize if the question is basic, but I am a beginner. I have a dataset of a bit less than 4500 records. This is a survey and ...
0
votes
0answers
14 views

Why is the Fisher exact test not always used in the cases where a chi squared is appropriate?

According to Wikipedia: Although in practice [Fisher's exact test] is employed when sample sizes are small, it is valid for all sample sizes. If Fisher's exact test can provide the exact ...
0
votes
0answers
5 views

Comparing density plots and scoring the combination

I have a set of density plots that contain the distribution of stock prices. Each graph has 5 density plots as follows that shows the distribution of monthly returns based on their ratings - ...
0
votes
0answers
2 views

Forced-choice data possible with confirmatory factor analysis?

I have a task where I ask participants to view a series of images. After viewing each image they are given several options with which they must a forced-choice as to which category the image falls ...
4
votes
4answers
80 views

What do these statements not follow logically from a 95% CI for the mean?

I've been reading Hoekstra et al's 2014 paper on "Robust misinterpretation of confidence intervals", which I downloaded from Wagenmakers's website. On the penultimate page the following image ...
0
votes
0answers
8 views

Is it valid to use Hartigans' dip test to reject uni-modal null hypothesis with large N?

first time questioner, so please be gentle :) I have two distributions of data from a simulation. By eye, one looks like it might be bimodal, one not. I copy them below A: parameter value 1 : by ...
0
votes
0answers
20 views

Hierarchical clustering of correlation matrix

I have a correlation matrix of 8,854 * 8,854 size. These are Pearson correlation coefficient values in the matrix. I want to perform Hierarchical clustering and create good resolution images like I ...
0
votes
0answers
24 views

Is the distribution of my residuals from a multiple regression normal?

I have a dataset with 17 variables (one numerical, 16 categorical). The numerical variable is the execution time of a process. I'm using one of the categorical variables (100 levels) to predict the ...
0
votes
0answers
6 views

Significance of the distribution of DNA sequences given a certain nucleotide bias

I have a large sequence of DNA in which every position can have 4 different states, or nucleotides (A,T, G or C). The distribution of the nucleotides in the sequence is non-random and, most ...
1
vote
0answers
10 views

How to test for serial correlation with pooled OLS, FE an RE?

I have pooled data for 3 years, and I have come across the problem of serial correlation. Some books mention the problem of serial correlation when pooling the data. My question is: is it possible to ...
0
votes
0answers
19 views

What's wrong with my Kernel algorithm (Kernel SVD)?

I have a user-item matrix $A$ as data input, which is a sparse matrix containing a large number of missing values (as zeros). Each row is a user, and each column is an item. Generally, I am conducting ...
0
votes
1answer
21 views

Five-number summary and mean

Why was not mean included in the five-number summary, when it was first conceived? What was the motivation of choosing sample minimum & maximum, lower & upper quartile and median?
3
votes
3answers
29 views

The sum of two symmetric random variables is symmetric

If $X$ and $Y$ are two random variables with probability density functions which are symmetric around their respective means, their sum, $X+Y$, has a probability density function which is symmetric ...
0
votes
0answers
5 views

LMG don't sum to model's R2

I have a regression model and I want to determine the relative importance of the predictors. I used the package relaimpo in r. The package says that 98.84% of the ...
0
votes
0answers
10 views

Digging deeper into the FitDist function

I am using the script allfitdist to find which distribution best fits my data according to the tests included (BIC, AIK etc...) - these all stem from the script ...
0
votes
0answers
10 views

Estimation of probability density function

How to estimate probability density function when we have set of feature vectors, but we don't know their statistical distribution?
0
votes
2answers
21 views

AB testing with R

I'm new with AB testing and i want to do this with R (free and easy to learn software). Can anyone help with sample code in R for AB testing? Thanks Ariel
0
votes
0answers
3 views

Research design regarding similar names and comovements

I have a small question about a small research that I wanted to do regarding stock symbol similarities and their abnormal returns. I have about a sample of 10 000 stocks and I calculate how much they ...
0
votes
1answer
13 views

Interpreting percentage units regressions

I am using a panel of 2249 schools with data from 2002-2008. Some of the schools are single sex schools whilst others are mixed sex. Some background on my regression: Consider the determinants of ...
0
votes
0answers
10 views

Does it make sense to perform a MTS algorithm on data that should need an MTMM algorithm?

Thanks to this topic Which package to use for convergent and discriminant validity in R? (and especially the answer of chl) I became aware of the existence of the mtmm function of the psy R package. ...
0
votes
0answers
6 views

Hierarchical clustering with NCD as the distance metric

I am trying to cluster a bunch of executable files, and I want to use NCD ( normalized compression distance) as the distance metric. Is there any software package which lets me do that? Thanks
2
votes
1answer
22 views

Converting log odds coefficients to probabilities

Suppose we've ran a logistic regression on some data where all predictors are nominal. With dummy coding the coefficients are ratios of log odds to the reference levels. A colleague claims that we can ...
0
votes
1answer
13 views

EFA: Can I remove/drop variables with non significant loadings and re-run the EFA?

I am employing EFA to 56 items. However, there were cross-loadings occurred and, therefore decision to drop the items is made. The question: The rotated components matrix showed there were a few items ...
1
vote
0answers
19 views

Which Non-parametric test to use with two Ordinal sets of data

I am trying to find which factors in Ques 6 are strongly related to company being rated high as compared to others in Ques 4 and similarly factors related to company being rated low.
0
votes
0answers
8 views

Why must the solutions of the characteristic equation be greater than 1 for an Auto-regressive model to be stationary?

According to my notes, stationarity occurs if: All the solutions of the characteristic equation of the $AR(P)$, $1-\phi_1X-\phi_2X^2-...-\phi_PX^P=0$, are greater than 1 in modulus. No ...
0
votes
0answers
13 views

country-time dummies and specification error

Currently, I am doing research about the impact of free trade agreements to trade flow. I have panel data that consist of 86 countries from 1980-2012. I use panel data estimation : Pooled Least ...
10
votes
2answers
280 views

Is the exact value of a 'p-value' meaningless?

I had a discussion with a statistician back in 2009 where he stated that the exact value of a p-value is irrelevant: the only thing that is important is whether it is significant or not. I.e. one ...
0
votes
0answers
8 views

R quantmod candlesticks do not plot; OHLC data seems unrecognized [migrated]

I am following a basic tutorial for R's quantmod package. I run into trouble using the candlestick plots however. It appears that ...
0
votes
1answer
29 views

What is $\text{cov}$$(\hat{y_i}, \hat{y_i}^*)$?

Using the simple linear regression model: $ {y_i}= {\beta_0} + {\beta_1}x_i + \epsilon_i$, where E[$\epsilon_i$]=0 and var[$\epsilon_i] = \sigma^2$... If $ \hat{y_i}= \hat{\beta_0} + ...
1
vote
1answer
28 views

Conceptual issues in AR model representation

Q1 : I am looking for a $k$ lagged (k order) AR model where k >2 conveniently k >20. I am unable to find any large AR model other than the popular second order AR model, $x_t = 0.195x_{t-1} - ...
0
votes
0answers
20 views

What is ${\rm cov}(e_i, \hat y_i)$ in simple linear regression?

The model is $y_i = \beta_0 + \beta_1x_i + \epsilon_i$ What is ${\rm cov}(e_i, \hat y_i)$? What is ${\rm cov}(\epsilon_i, \hat \beta_1)$? What is ${\rm cov}(e_i, \epsilon_i)$? For 1, I am writing ...
0
votes
1answer
12 views

how to transform data of two experimental groups? one is positively skewed and one is negatively..

I have two experimental groups. Then I test their normality respectively. Result shows that one is positively skewed and the other is negatively skewed. In this case, how should I do the data ...
-2
votes
0answers
18 views

Fitted coefficients [on hold]

(b) The fitted coefficients and summary table including t-statistics and the overall F statistic for the fit etc. (c) Appropriate diagnostic plots. (d) Description of any action taken, as a result ...
0
votes
0answers
10 views

Are there any packages in R to use Apache Shark?

I would like to data mine Apache Shark with R but I'm not sure if there any packages available for R. Does anyone know of any? Thanks
-1
votes
0answers
22 views

Diagnostic plot includes outliers

Write a short report of your analysis which should include; (a) Plots of the response versus each of the predictors. (b) The fitted coefficients and summary table including t-statistics and the ...
0
votes
0answers
11 views

Probability of Event from a Chi-Square Table

I have the following table: From here I want to answer the following question: P(CHILD CAN RECOG BEG SOUNDS OF WORDS – YES | CHILD RECOGNIZES LETTERS - Most of them). From my understanding of ...
2
votes
0answers
22 views

Why linear transformation can improve classification accuracy when the dimensionality of data is high?

Let $X$ be an $m\times n$ ($m$: number of records, and $n$: number of attributes) dataset. When the number of attributes $n$ is large and the dataset $X$ is noisy, classification gets more ...
2
votes
1answer
6 views

What quantifies a stable parameter?

I'm optimizing 5 parameters for an option pricing model. Now I want to asses whether these parameters are stable over time (i.e., a year). For this I create about 12 subsamples and estimate the ...

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