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Questions tagged [non-independent]

Data, events, processes, etc, are non-independent if knowledge of 1 provides some information about the state or value of the other.

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When does $E[f(X_i)]=E[f(X_j)], i\neq j$?

Suppose we have random variables $X_1, \dots, X_N$, with joint probability distribution $F_{X_1,\dots,X_N}$. Under what conditions does the following equality holds? $$E[f(X_i)]=E[f(X_j)],\ \ i\neq ...
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Clustering items based on response behavior on three tasks

I have a question and was hoping someone could point me in an appropriate direction. I conducted a large experiment and would now like to find patterns in the response behavior of the subjects. The ...
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10 views

how to handle non-independent experimental data

I have data to analyse that involves 12 treatments. Each treatment was "replicated" 3 times, for 36 observations. But the experiment involved applying the treatment to 1 side of an object -- and most ...
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3answers
184 views

How to test the equality of two Pearson correlation coefficients computed from the same sample?

Is there a reliable way to say if two Pearson correlations from the same sample (do not) differ significantly? More concrete, I calculated the correlation between a total score on a questionnaire and ...
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1answer
19 views

Estimation of model with non linear dependent variable

I am trying to verify whether two variables are linked by a relation of the type: |y|=ax or y^2=ax. What could be the right statistical procedure to verify whether the above relations are correct and ...
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10 views

Why dependencies would cancel while paramterizing CPD?

Consider that in CPTs of a Bayes Net(structure is fixed) one dependence is fix(parameters are set for $P(X|Y)$) and we are parameterizing other CPDs, is it possible that the other parameters would ...
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185 views

Regression with dependent data with low dependence

Suppose you have data that is grouped in one way or another and therefore the assumption of independence is suspect. But you look at the intraclass correlation (or autocorrelation) and it is very ...
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2answers
62 views

Can statistical dependence arise only at the limit?

(This has been inspired by a comment exchange with @guy). Assume we have two infinite sequences of random variables, $\{X_n\}$ and $\{Y_n\}$. Assume the RVs in $\{X_n\}$ are statistically ...
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11 views

Compare categorical variables that are not(?) independent

I have some survey data in which respondents were classified in to two overlapping groups (i.e. respondents who work in a profession and people who do this same work on their own-- many people do ...
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0answers
5 views

Which test to run for effect of nominal independent variable on multiple ordinal dependent variables

Im new to stats so dont shoot me. I am trying to work out what is the correct test to run in the following scenario Does the independent nominal variable of colour, with four categories (Blue, Brown, ...
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8 views

statistics of (possibly) non-independent interacting systems with fat tails

I apologize if this question has already been asked. I don't know the proper terminology to find my answer - so if it has, please direct me to it! Problem setup: I have many time series of a ...
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Can two variables be included in same model when if binary B=0, continuous C>0 and when B=1, C=0?

I am interested in looking at the effect of both a binary predictor ("B") and a continuous predictor ("C") on an outcome. However, the value of C is conditional on B in that for B=1, C=0; for B=0, C>0....
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Standardised effect size and CI for non-independent longitudinal data in a linear mixed-effect model (LMM)

I would like to calculate standardised effect sizes with confidence intervals for fixed effects in a linear mixed effect model (LMM) for data that have an unbalanced repeated measures longitudinal ...
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1answer
63 views

Govt. organisation favouritism in its complaint handling

I am analysing some data for a government organisation and trying to convince them that their complaint decisions are biased. I believe they favour certain organisations. I have put together the ...
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0answers
12 views

Two correlated ordinal independent variables, several continuous dependent variables

I am currently struggling with a somewhat atypical analysis. People have been evaluating their cognitive state at two time periods – when they had attended school and at the present moment. Naturally, ...
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1answer
25 views

What stats method to apply when measuring a trait multiple times from the same individual?

I have 2 species of wildflowers. Using scanning electron microscopy. I took images of the petal surface. On the petal surface I measured the height and width of individual cells. I have 1 to 3 ...
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0answers
17 views

Cross-Sectional Dependence Test in Panel-Data Models

I did cross section Dependence test in Eviews for panel data (EGLS Model) and Breusch-Pagan LM test, Pesaran scaled LM test, Bias-corrected scaled LM test confirmed the cross-section dependece but ...
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19 views

Accounting for factors that could be driving a difference between two means

just restarted data analysis so I've lost my edge quite a bit. Anyway, I've come across a problem and Im a bit stumped. I have a dataset for adverts. I want to measure the uplift in conversion ...
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28 views

non-parametric tests for repeated observations

I am looking for an RM-ANOVA alternative that fits with non-normal data that may not satisfy sphericity assumption. My dataset: Through a mark and recapture study, I trapped turtles, and collected ...
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0answers
10 views

Comparing means of two experiments over time using LME

I have conducted a lab study on ocean warming and corals using an aquaria tower with 3 levels á 4 aquaria. Each level depicted one temperature treatment (2 heat treatments and 1 control): Level 1 = ...
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0answers
35 views

Is this exercise question well-posed? Dependence of marginal normals with correlation $\rho$

An exercise question asks me to find the tail-dependence of $X$ and $Y$, where $\operatorname{Corr}(X, Y) = \rho$, and both $X$ and $Y$ are standard normal variables. The tail-dependence is $$ \lim_{...
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31 views

Testing statistical independence before using ICA

First a little bit of background. I'm interested in exploring the performance of Independent Component Analysis (ICA) in the context of disentangling intracranial EEG signals. These signals are ...
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0answers
11 views

Statistical test to compare dependent samples

I am comparing by race the number of limbs (4 total - including both arms and both legs) affected by condition X. Some patients contribute 4, some 1, and some somewhere in between. I want to compare ...
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0answers
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Correcting for sample overlap (loss of statistical independence) in two z-tests

Short form: How can I correct two p-values computed from normal distributions to account for the fact that part of the samples overlap? Long form: I have a sequence of i.i.d RVs of length $n$. The ...
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172 views

Dependent vs Independent events (Conditional Probability using a pair of dice)

I am watching this video on YouTube to understand dependent and independent events and conditional probability. The example author uses is of a pair of dice. There are 2 dice, Red and Green, let's ...
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1answer
28 views

Which statistical method should use to compare two dependent data (from 1 patient) but not paired?

I want to compare the number of lesions worsening and non worsening on superior to inferior side of the eye of a group of patients. I want to compare if the proportional results (the total sum of ...
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1answer
27 views

Are basic multilayer perceptrons well-suited to prediction of non-independent events?

Multilayer perceptrons are great for discovering associations between variables defining independent events based on the same underlying associations in reality. Less cryptically put, MLP's are great ...
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0answers
63 views

Expectation of the minimum of dependent random variables

How do we compute the expectation of the minimum of dependent random variables? In other words, what is the value of $\mathbb{E}[Y]$ in the following case: $$ \mathbb{E}[Y]= \mathbb{E}\big[\min(X_1,\ ...
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0answers
57 views

Critical value for Mann's test against trend

To test that a sample $X_1,\ldots,X_n$ are i.i.d against that the distributions of $X_i$ are stochastically increasing in $i$, how to find the distribution of the test statistic and the critical value ...
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0answers
14 views

Variables relationship in large multidimensional datasets

Suppose I have quite a large time series (e.g., daily car accident rates in London for the past 20 years) and I also have further datasets for the same time period (e.g., daily precipitation, wind ...
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0answers
18 views

Compare treatment effects across Levels of aggregation

Suppose I am running an experiment to see if a treatment changes the mean weight of a group of people. Note that I am specifically interested in the mean weight: if half the people get heavier, and ...
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1answer
36 views

Can ANOVA be used for percent frequency data?

Problem: Suppose there are three restaurants in a town. I conduct a survey by asking each person what percentage of time you eat in restaurant A, restaurant B and restaurant C. The percentages for ...
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0answers
9 views

How to compare 3 dependent conditions?

I have the result of an experiment for N subjects. The experiment results in 3 possibilities, the subject choose A, B or C. For each subject, the experiment is repeated 10 times. So I have ...
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1answer
89 views

re-analysis of someone else's data: 5 treatments x 4 non-exclusive outcomes

I am trying to re-analyze (ETA: used loosely; the original study performed no statistical analysis) some published biological data (below). They used 5 treatments and scored presence/absence of 4 non-...
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1answer
114 views

Testing the equality of two regression coefficients from same data but different frequency

I am using tick data of implied volatility and their underlying asset price and extract 2 data sets of hourly frequency and daily frequency. The 2 data sets are formed from the same tick data. I run ...
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1answer
136 views

Different (Welch's) ANOVA tests and post hoc contradict paired tests. Which one to accept?

This is a problem that I think nothing would help but sharing my data here. I have 3 groups (n=7) which are paired. They are concentrations of a chemical compound in different parts fish tissue. For ...
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0answers
27 views

Friedman test when subjects are not a random sample from a population/ when subjects are dependent

Imagine that you measure all $n$ people from a school class in $k$ $\geq2$ different treatment conditions. My goal is to find out whether the there is a systematic difference in Ranks (i.e. the $H_0$ ...
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1answer
57 views

A special case of the law of large numbers for (possibly) dependent, identically distributed random variables

I want to show that $\dfrac{1}{N}\sum\limits_i^N x_iw_i \to 0$ as $N\to\infty$, where $w_i\sim \mathcal{N}(0,\sigma^2)$, $\mathbb{E}[x_i] = 0$ and $\mathbb{E}[x_i^2] = \rho$. The $x_i$s are ...
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How to minimize dependency between existing model and retraining dataset (using fraud modeling as example)?

What are methods to minimize dependencies between the existing model in production and the data that will be used for retraining future models (when future samples are created based on the existing ...
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0answers
80 views

p value for non-independent simulations of kendall tau correlation

I want to work out Kendall's tau b for some sets of variables. In each case, I am building my sample from two sub-populations, where one of the sub-populations is larger than the other. For the ...
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0answers
65 views

Regularized regression with dependent data/cases

I want to estimate a regularized lasso regression model using nested cross validation to determine the best lambda and to get an estimate of internal validity. Specifically I have a binary outcome (...
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0answers
6 views

Intratumor heterogenity in ordinal scaled histology dataset? Cluster analysis for non independent observations?

I got my hands on a histology dataset and we want to analyze the heterogenity within brain tumors. My current but growing dataset contains 116 records from 29 patients. The tissues are dyed and ...
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1answer
106 views

Strange results when applying Wilcoxon test in R

I am interested in whether the mean of one sample is statistically greater than the mean of the other one. The samples are not independent in that if the ith observation in sample A is positive, than ...
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1answer
55 views

Interdependence in binomial regression

I am having trouble accounting for interdependence in data that I would like to model with binomial regression. I am looking at school attendance during two months (43 school days), counting whether a ...
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0answers
24 views

Dependency of Samples

I am biometrics researcher, I compared normal faces with expressive faces and I achieved 6 samples: Normal vs Normal scores Normal vs Angry scores . . . Normal vs Happy Scores Can I use Two sample ...
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0answers
24 views

Non parametric tests for relation/association between variable

What could be an appropriate test for checking whether there exist any relationship between Net Promoter Score ( Categorical in nature with 0 meaning detractor, 1 meaning Neutral, 2 meaning Promter ) ...
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0answers
50 views

Correlation between dependent predictor variable and dependent response variable in repeated measures experiment

I would like to determine if there is a significant relationship between a measured continuous variable (predictor variable) and a response variable, which are both measured over time and therefore ...
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0answers
9 views

Consequence of validating a predictive algorithm on non-independent data?

What are the consequence of validating a predictive algorithm (binary classification) on non-independent data? The algorithm has already been developed elsewhere and it does not incorporate ...
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1answer
60 views

Dependency between quantitative and categorial variable

I have a data set with a categorical variable $C$ (approx. 8 levels) and a quantitative variable $X$. I suspect that $X$ and $C$ are strongly dependent. How can I verify this hypothesis? My approach ...
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0answers
50 views

Joint probability/ conditional probability of correlated events

I have drug A and drug B that I tested on many types of bacteria. I know that the survival percentages are correlated with Pearson's r of 0.77 I want to predict the survival percentages when I'm ...