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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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ANOVA with dependent means?

I want to perform an ANOVA test on where hospital equipment is located within a hospital on different days of the week and months of the year. My dependent variable is the proportion of equipment in ...
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10 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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15 views

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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45 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
26 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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9 views

Appropriate statistical test for frequencies of motifs

I have a graph composed of 26 nodes, labelled A to Z. Some nodes are connected by edges, but not all nodes are connected to all other nodes. I enumerate all possible sub-graphs comprised of four ...
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1answer
21 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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55 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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22 views

Ratio error propagation for dependent, paired variables

I've been struggling for some days with a statistical issue that is beyond my knowledge. Context: I'm studying the volume of cells, as well as their nucleus volume. These cells are categorized in 3 ...
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20 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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12 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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14 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
25 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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8 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
76 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
56 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
85 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
16 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
48 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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12 views

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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74 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
61 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
91 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
50 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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22 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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21 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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44 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
36 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
36 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 ...
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0answers
16 views

Accounting for nonindependence when comparing groups

I have 6 individual animals that I am estimating home range size for. For each animal, I calculate a home range size over a two week period, so that each individual ends up having two home range size ...
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0answers
11 views

Dependent variable is dependent from the outcome of other dependent variables

I have a problem with formulating my problem, so I cannot search for a solution. Here is my issue: I would like to analyze the impact of the user behaviour of cars on the error rate of its components....
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1answer
60 views

Multiple values in a variable for linear regression

Say I have a data set that I am trying to perform a linear least squares regression on. Suppose that the end goal is to predict y from x. The training data set I am working with has the form ...
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25 views

Variance of grouped or hierarchical data

I'm coming at this from a non-pure stats background, so apologies if it's a simple problem.. Imagine there are 5 students who take 10 exams each. This gives a sample of 50 marks. I can naively ...
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1answer
49 views

Are samples dependent or independent, paired or unpaired?

An animal performs a task in a T-maze. Sometimes he chooses the right part of the maze (right trials) and sometimes left(left trials). I want to know if there are differences in firing rate of one ...
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39 views

Statistic analysis on dependent and simultaneously independent data

Let's assume that I have a datasheet looking like that: ...
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0answers
47 views

Meta-analysis: Correlated controls, correlated treatment: How to specify variance-covariance?

Goal The goal is meta-analysis of slope coefficients that I calculate from multiple treatments and controls from multiple studies. I'm looking at the relationship between x broadly and y broadly, ...
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1answer
101 views

Multivariate Gaussian Copulas to model dependent random variables

Assume that the probability distributions of several random variables and their correlation matrix are known, say $x_1\sim\text{lognormal}(1,1)$, $x_2\sim \text{uniform}(1,2)$, $x_3\sim\text{Beta}...
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1answer
110 views

Are random subject intercepts enough to account for non-independence when modelling trial level data?

I know that when analyzing trial level data (i.e., treating every observation of a given individual as a separate data point), something must be done to account for this non-independence. I've always ...
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1answer
141 views

Binomial distribution for dependent trials?

Imagine a bag has some balls, some blue some red. Lets say there are 50 balls. 5 are red and 45 are blue. I have 4 bins, and am going to randomly pick balls out of the bag and put them into the bins ...
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1answer
26 views

Are my samples dependent or independent?

I have an assignment where I have car brands (Honda, Hyundai, Audi etc..), category (sportscar,hatchback, convertible etc..) and brand type(electric, non-electric). I want to determine the ...
3
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1answer
170 views

When is the product XY of two continuous random variables uncorrelated with X?

Let $X$, $Y$ be two independent random variables defined on the real line by a fixed distribution $\mathcal{D}$. Let $Z = XY$, the product of $X$ and $Y$. For which choices of $\mathcal{D}$ is $Z$ ...
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1answer
17 views

Correlation between different variables and among the group

I'm not a statistician, just a learner and facing problem in my research. I performed experiment on 25 subjects and collected data from 3 different locations (muscles, say A, B, C). The experiment ...
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0answers
12 views

Correlation with data that show an effect of the factor that they are being pooled across

I am analyzing concentrations of a chemical in a plant species and am interested in understanding how the concentrations vary between tissues and across sites. An ...
2
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0answers
19 views

Dependence structure Markov switching models

In the literature I read that the observation $\epsilon_n$ depends both on the hidden process $\Delta_n$ and the lagged observations $\epsilon_{n−1}$, it is called Markov Switching Model. So ...
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1answer
34 views

Can the Mann-Whitney Test be used with small n or loose independence?

I have data on market share. I would like to compare a firm's mean market share before and after an event. The data is quarterly and I have only been provided with 16 observations, 8 before the ...
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0answers
46 views

Correlation between non-independent time series data

I have count data on the number of individuals showing 5 different ventral colourations in a free-ranging populations of lizards across 12 years. As the data was collected in the same population, the ...
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0answers
27 views

elite survey, pooling data without sufficient info to form a panel

i am working with a political candidate study which surveyed all candidates running at an election. I got two consecutive waves, or in other words, data for two elections. The response rates are about ...
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0answers
6 views

How to handle local item dependence?

I have administered a video-based multi-item test which is sequential in nature (each video builds on the previous one). Participants watch short videos and then answer a question after each video. I ...