0
votes
0answers
2 views

Using single line chart with multiple, unrelated, data sets?

I would like to visualize two unrelated sets of data using a single line chart to check for any "correlation" (it's just for fun - nothing that claims to be statistically accurate). Just as an ...
1
vote
0answers
6 views

Slope analysis where one group is not normally distributed

I am currently doing analysis of five separate drug groups and their changes in levels of prescription over time. Having done linear regression on excel I am comparing the 'steepness' (m) of the ...
0
votes
0answers
3 views

Effect size of a cluster with respect to the whole dataset

I mainly am a machine learning guy and my knowledge of statistics is a bit limited. I have a (small) dataset of objects described by two categorical variables: $$ \begin{array}{|l|l|l|l|l|} \hline ...
0
votes
0answers
2 views

Learning from streams with concept drift in real world - how to handle missing class problem?

In currently delves into learning from streams with concept drift. As more I learn I think about how I can use learning algorithms on real data. Most of drift detection algoritms to evaluate is ...
0
votes
0answers
3 views

i have problem of my sampling based on secondary data

good afternoon for all i have question and i hope i get the answer i am doing my thesis about the imapct of liquidity risk in islamic banks in GCC countries and i have choose just two countries one ...
0
votes
0answers
11 views

What statistics should i use to compare

I am currently analyzing leaf senescence over two sites, using 6 species, each with 5 replicates. The senescence is measured in percentages, and is linear. I was just wondering if anyone knew how i ...
0
votes
0answers
9 views

Random walk forecast with bootstrapped steps

I am looking for a reference (or comments) on using bootstrapped residuals as steps for $x_{t+1}$ random walk forecasts. The idea is to forecast $$ x_{t+1} = x_t + r $$ where $r$ is a draw from ...
3
votes
1answer
23 views

random walk estimation with ar(1)

when I estimate a RW with an ar(1) the coefficient is very close to 1 but always minor. What is the math reason that the coefficient is not greater than one?
0
votes
0answers
11 views

Sample size needed to validate classification/prediction model

Dose any rule of thumb exist (or possible calculation) regarding sample size needed to validate an binary classification model. We have developed this prediction model for a medical condition and ...
0
votes
0answers
6 views

Log transformation on variable in percentage units

I was working through my STAT course and I got curious about this... I have seen lot of people use transformations on the variables in regression especially using logarithms, and usually the ...
0
votes
0answers
8 views

Correlated time series at different aggregation levels

Correlated time series at different aggregation levels Hi, In my time series data I discovered the following behaviour. My time series are available in 500ms intervals and are about sensor data like ...
0
votes
0answers
14 views

Why Binning Variables in Predictive Analytics?

Lot of discussion in CrossValidated focuses on optimal binning methods, binning example etc. But I am trying to figure out what are the scenarios that I have to bin variables whereas it's better idea ...
0
votes
0answers
8 views

Zero Inflated Poisson or Negative Binomial Regression model in Panel Data

I am using the Stata version 13.1. My data is count in nature and also it is a balanced panel. However, my data suffers from the problem of excess zeros and also suffers the problem of overdispersion. ...
0
votes
0answers
5 views

Interpretation of multinomial probit using MNP package

I used MNP to analyze the election in 1992 and I want to know the probability that non-partisan voters vote for Bush when the personal economic condition varies and the effect of education is ...
0
votes
1answer
19 views

Need help in understanding continuous-dummy interaction in OLS regression

I am having some conceptual difficulties in understanding and interpreting interaction terms (between a dummy and a continuous variable) in OLS regressions. I was hoping someone could help me out. I ...
2
votes
0answers
22 views

Distribution ratio of $\bar{y}$ and $S_x$ when $X$ and $Y$ are correlated normally distributed

If we have two correlated $X\sim N(\mu_2,\sigma^2_2)$ and $Y\sim N(\mu_1,\sigma^2_1)$ with correlation $\rho$, then $\bar{y}$ has $N(\mu_1,\frac{\sigma^2_1}n)$ and $S_x$ follows ...
4
votes
2answers
41 views

What are good examples to show to undergraduate students?

I am going to teach statistics as a teaching assistant for the second half of this semester to CS-oriented undergraduate students. Most of the students took the class has no incentive to learn the ...
1
vote
1answer
13 views

Model selection and assumed parameters in models

Suppose there are four models: Model 1: $y = ax$ Model 2: $y = ax^2$ Model 3: $y = a\sqrt{x}$ Model 4: $y = ax^\theta$ Model 4 is the most complex model with two parameters (the others have ...
0
votes
0answers
10 views

advices about train set and validation set

I know that there should be three sets of tests for supervised learning that are: train validation test I have read that for example in the case of NN in the train phase one chooses the weights ...
1
vote
2answers
23 views

Second moment from survival function

Let X be a non-negative continuous random variable with probability density function f(x). Let $$G(t) = \int_{t}^{\infty} f(x)dx$$ Show that$$E(X^{2}) = 2\int_{0}^{\infty} tG(t)dt$$ My thoughts: I ...
0
votes
0answers
9 views

Regression choice with endogenous variables

I am attempting to analyze the relationship between the quantity of oil demanded and the price of oil. The price of oil is an obvious endogenous variable, so regressing (OLS) quantity on price (with ...
0
votes
0answers
16 views

Hypothesis Testing for small sample

I am a somewhat dubious about how to apply some hypothesis testing for this case or maybe it is not applicable at all. In an undergraduate Algebra course, the Faculty has been using a book from ...
0
votes
1answer
18 views

Does this variable follow a poisson distribution or a binomial distribution?

I dance an average of 2/7 nights during a week. D = Number of nights dancing in one month/4 weeks. My first thought was Poisson, but am now unsure. Is it none of the above?
0
votes
1answer
11 views

Skewed Classification Problem

So I've read around and seen this is a problem. I have a classification problem and 12 variables ... I'm working on getting more, but even if l get the number to 20-30 I feel like the problem will ...
0
votes
0answers
11 views

Overlapping interval of a Poisson arrival process

Calls arrives according to a Poisson arrival process with rate lambda = 15. Find E(N(2,4]N(3,5]) My thoughts: E(N(2,4]) = E(N(3,5]) = lambda * t = 15 * 2 = 30 However, I cannot figure out the next ...
0
votes
1answer
14 views

problems in doing logistic regression with unbalanced sample, give me some references

I have a dataset with lots Y=0 and few Y=1. I have to run logistic regression, so I'm using a retrospective sample in order to get a more balanced sample. Could someone give me some references that ...
1
vote
1answer
10 views

Is my interpretation of the numerical gradient versus network output correct?

I have implemented a neural network with back propagation using a sigmoid activation function. To validate the functionality of my code, I am estimating the gradient of my function using the ...
0
votes
0answers
3 views

Which statistical test for statistical significance of positive result in 5 categories of samples

I have 5 categories rock samples and I am trying to understand how their fossil preservation differs and whether the difference is statistically significant. I determined the presence or absence of ...
1
vote
3answers
19 views

Sample size of sampling distribution of the sample mean

When people say that the mean of the sampling distribution of the sample mean is equal to the population mean, is this true regardless of how small or large the size of the samples are? I'm having a ...
1
vote
1answer
42 views

Why do we need confidence intervals?

I am following a video lecture on Statistics, which introduces the concept of confidence intervals in the following way: "A bank vice president is interested in the average checking account balance ...
0
votes
0answers
7 views

Determine statistical significance of web server response times

I am trying to analyze the performance of a web server. I've pulled from the logs a sampling over seven days of the hits for each individual page. From a histogram of the response times, I see that is ...
0
votes
1answer
22 views

Is my data normal graphical vs. analytical test

I am trying to determine if my data is normal. I am using R. I run the jarque bera test that has a NULL hypothesis of Normality ...
0
votes
0answers
15 views

Time-partitions of sample size

I am struggling with explain something I read in a Whitepaper. The essence is as follows. Let's begin with a random variable $X$ defined as number of events in an hours. Further, we assume that $X ...
0
votes
0answers
3 views

summary on correctly classfied instances WEKA for a 10fold cross-validation

I ran a 10fold cross-validation BayesNet (but it could be any method in WEKA) and the output i got was (among other things): ...
0
votes
1answer
14 views

How to do power analysis for two-way analysis of variance?

The pwr library can be used to do power analyses when testing with 1-way analysis of variance. Are there similar libraries for 2-way ANOVAs? How could I got about doing this in R?
0
votes
0answers
10 views

Statistical test to check if mean of two groups are “significantly” same [duplicate]

Is there a statistical test, to check mean of two group is "sigificantly" same. Something opposite to Wilcoxon test. I was thinking may be running Wilcox test and if it not significant, then check the ...
1
vote
1answer
49 views

Likelihood ratio tests using ML vs. REML

I am using Mixed effects models (nlme package in R) to choose the model with the best random and fixed effects. I am following the procedure of Zurr et al. (2009) ...
0
votes
0answers
12 views

Test if two means are significantly different in R [duplicate]

I would like to test if two means are significantly different from each other. I am using R and I do this: t.test(SampleA,SampleB) and I get output that looks ...
0
votes
0answers
14 views

Comparison of observations in subgroups?

I have two groups, group A and group B. Each group is composed of subgroups, say A1, ..., An and B1, ..., Bm. Within each subgroup we have a different number of observations, say A1 would contain ...
0
votes
0answers
12 views

Summary statistics for imputed data from Zelig & Amelia [migrated]

I'm using Amelia to impute the missing values. While I'm able to use Zelig and Amelia to do some calculations... How do I use these packages to find the pooled means and standard deviations of the ...
0
votes
0answers
12 views

Different types of dependent observations [on hold]

Say we collect 50 observations. If all 50 observations were collected from the same person, then they would be dependent. In this case, we would expect the type of dependency to be a positive ...
0
votes
1answer
17 views

categorical data normalization in SVM Classification [on hold]

I have a set of features (contineous + categorical)...I have converted the different categories to numerical, for example (object1, object2, object3) = (1,2,3)..etc. and ran SVM... I obtain high SVM ...
0
votes
0answers
9 views

Plot histogram using ggplots to be similar as hist() in R base [migrated]

I am new with ggplot2. I am using it to plot a histogram. Here is the code ...
0
votes
0answers
22 views

Sampling massive dataset [on hold]

I have a massive dataset (100s of millions of rows and 100s of dimensions). The dimensions are of all conceivable data types. I need to sample the data for predicting a response. How do I arrive at ...
1
vote
1answer
29 views

Closed form solution for t-stats and p-values in multiple regression

I am trying to build a spreadsheet that will perform multiple linear regressions on a number of data series using the closed-form solution. It was fairly straightforward to write the solution for the ...
0
votes
0answers
12 views

A chi-squared test for a matrix of data

Given a observable vector $v=[v_1,v_2,\ldots,v_n]$ and a model $m=[m_1, m_2,\ldots, m_n]$ when $\sum_i v_i=\sum_i m_i$, I can use chi-squared to determine the likelihood that $m$ is a good model for ...
0
votes
0answers
4 views

Choice based conjoint latent class analysis in R

How can we perform Latent class Analysis for choice based conjoint data, to both segment respondents and determine co-efficients for attributes at the same point of time? I know there is a package ...
1
vote
0answers
13 views

How can I test for changes in the distribution of categorical data over time?

Each week at my organization, we receive X number of type A messages, Y number of type B messages, Z number of type C messages...etc. I want to be able to test if the distribution of these message ...
1
vote
1answer
11 views

Using contingency tables for testing multiple dependencies

I know that I can determine the correlation / association / dependency between two variables (X= smoker, and Y=cancer) using chi-squared with a 2x2 contingency table: ...
0
votes
1answer
18 views

how to analyze the results for this binomial test?

I have established the following hypothesis: The probability of successfully passing the course in this trial is less than 50% (alternative hypothesis) The probability of failing the course in this ...

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