Questions tagged [bimodal]

A bimodal distribution is a probability distribution with two different modes. These appear as distinct peaks (local maxima) in the probability density function for continuous distributions and the probability mass function for discrete distributions..

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Test for bimodal distribution

I wonder if there is any statistical test to "test" the significance of a bimodal distribution. I mean, How much my data meets the bimodal distribution or not? If so, is there any test in the R ...
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1answer
2k views

If the distribution of test statistic is bimodal, does p-value mean anything?

P-value is defined the probability of obtaining a test-statistic at least as extreme as what is observed, assuming null-hypothesis is true. In other words, $$P( X \ge t | H_0 )$$ But what if the test-...
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2answers
178 views

Causes of bimodal distributions when bootstrapping a meta-analysis model

I help a colleague to bootstrap a meta-analysis mixed-effects model using the metafor R package framework authored by @Wolfgang. Interestingly and worryingly, for one of the model's coefficients I ...
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2answers
2k views

a perfect or symmetric bimodal distribution

I would like to know how I can measure the degree of symmetry of a bimodal distribution. Is there any a criterion like for example skewness in the case of unimodal distributions?
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1answer
2k views

What are some standard bimodal distributions?

I have plotted this curve using the default kernel density estimate function in R I am looking for some standard distribution which could be close to this. Is there any standard bimodal distribution ?...
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0answers
54 views

Determine if a series of discrete distributions are expected

*I apologize for the length of this post and I have almost no statistics experience, please keep that in mind :) In competitive diving, a diver will perform 5 different dives and will receive scores ...
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0answers
270 views

Quantification of “modality” of distribution

Does anyone know of a quantification of the modality of a distribution? For example, exactly how "high" must the "second" peak be in order to qualify as bimodal rather than unimodal with some un-...
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0answers
410 views

Test for differences in distributions; three samples; multimodal distributions

Here is a question on how to test for differences in distribution between three samples of multimodal distributed data. I have conducted a dictator game (http://en.wikipedia.org/wiki/Dictator_game) ...
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3answers
2k views

How to interpret histogram and normaltest result?

I investigated dataset using histogram and normaltest. I used scipy.stats.normaltest, got this result: ...
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2answers
720 views

Simulating a bimodal distribution in the range of [1;5] in R

I want to simulate a continuous data set/variable with lower/upper bounds of [1;5], while at the same time ensure that the drawn distribution can be considered as bimodal. Searching for my problem, I ...
2
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1answer
76 views

Modeling bimodal time-to-event

Here is a plot of death registration frequencies by age for the UK in 1974. I see distributions like this quite often: there is some event (e.g. death) which happens either close to birth, or ...
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1answer
59 views

Bimodal MaxEnt distributions?

What kind of constrains give rise to bimodal distributions in the Maximum Entropy formalism? Are there any known results in this topic?
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1answer
628 views

Similarity measures between bimodal distributions

I have to compare two bimodal distributions. So far, I have found the Bimodality Coefficient: $$ BC = \frac{\mu_{3}^{2} + 1}{\mu_{4} + 3\frac{(n-1)^2}{(n-2)(n-3)}}, $$ with $\mu_{3}$ referring to ...
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2answers
242 views

Choosing center of histogram bins for fitting

I have a bimodal distribution, and if plotted with Mathematica it looks like this: Now, the lowest value from the actual data is 8196 and 690720, but as seen in the plot, Mathematica lets the data ...
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1answer
2k views

Is this a multimodal distribution?

This histogram is part of a task about descriptive statistics. I thought it would be easy, and it is, but i am not sure about this one. First I described this histogram as slightly positively skewed. ...
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0answers
35 views

Multimodality of mixtures of more than two Normal distributions

Let $$\phi(x;\mu,\sigma) = \frac{1}{\sigma \sqrt{2\pi}} \exp \left(- \frac{(x-\mu)^2}{2\sigma^2}\right)$$ denote the Gaussian density function ($\sigma > 0$). Let $$f(x) = \sum_{i=1}^N p_i \...
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1answer
61 views

How to statistically distinguish between two types of time series (bimodal vs. not bimodal)?

I have two different types of time series. The first group of series is much more bimodal, and the second group is much flatter. For a given time series, I want to test whether it more likely belongs ...
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0answers
42 views

Observing seasonality in a time series

I've got a time series which plots surface reflectance over time. Ideally surface reflectance is high in the winter and is low in the summer, and is fairly constant during both of those periods. I ...
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0answers
628 views

fitting mixture of bimodal distribution

I am trying to fit my data with a bimodal distribution using two beta distributions, however it seems to me that the two peaks are not captured very well. The reason that I notice from the data is ...
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0answers
169 views

Build a model with bimodal output

Let's say that you want to build a model that predicts two possible outcomes with a probability for each. To be clear, i'm not talking about a problem where the target variable is binary and you want ...
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1answer
830 views

Is this a skewed distirbution or bimodal?

It appears that this distribution may be right skewed and bimodal. Or is it just right skewed only?
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1answer
92 views

What are the ways to model bi-modal target distribution

The target i am trying to regress is clearly a bi-modal distribution, currently one standalone model is giving results which are satisfactory. As I am seeking improvement on my present model, I want ...
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0answers
15 views

How to find groups inside the dataset (test for bi-multimodality)

I have non-normally distributed dataset, a record of a parameter, e. g. 50 subjects reacted to stimulation, (9 periods of time in total). So I have a matrix of 50x9 numbers, 9 medians for each time-...
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26 views

One dataset, two populations?

Setting: I have a single dataset from a simulation that appears to demonstrate bimodality. The dataset is composed of N measurements calculated at n different times and is two dimensional (N by n). At ...
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163 views

Bimodal distribution dispersion

what is the correct way to study the variability of a data set when all the observations are distributed like a bimodal distribution? For instance, here I identified the two modes as central index. ...
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0answers
277 views

Bimodal posterior distribution

Do you know in which situations is it possible to have a bimodal posterior distribution for some parameters? I couldn't find any information on the web. Thanks for your help.
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154 views

Modes and antimodes in apparent trimodal distribution with R

Suppose I have the following white blood cell counts: ...
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3answers
136 views

Detecting if an 1-dimenisional distribution is Multimodal

I'm writing up some C++ code for one of my Master's coursework. What I'm actually doing at the moment isn't on the syllabus, but I wish to implement it anyway as it will allow me to produce my own ...
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122 views

Geometric mean appropriateness with bimodally distributed data

I am trying to find out whether the performance of the geometric mean of a distribution as a measure of its central tendency would be impaired by the distribution being multimodal. For example, ...
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0answers
41 views

variance of a mixture in terms of the mean and variance of each component

I am following the MATLAB example to fit a mixture of two normal distribution that you can find here At some point it is defined the inital guess for the standard deviation as: ...
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0answers
315 views

How to deal with multi-modal distributions in hypothesis testing?

Say that I collected random variable X from one population and a random variable Y from another population. I want to apply a statistical test to determine whether these two populations are different....
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272 views

PCA on bimodal data: how to standardize the data?

My set of data points can roughly be broken up into 2 sets with different means. In each set, the points are close to each other (geometrically). Moreover, the variance is the same across both sets of ...
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0answers
29 views

Help with a bimodal IV - multiple regression [duplicate]

I am currently analysing some data including the Autism Quotient, which is a continuous measure. I plan to analyse via hierarchical regression. I have assessed normality statistically and both skew ...
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2answers
3k views

How to tell if data is unimodal vs bimodal?

I graphed a variable and it looked kind of bimodal but I'm not sure. Is there a more quantitative method of establishing this? Once again, I'm using Minitab.
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1answer
29 views

Testing for difference in means with bimodally distributed data?

I have two bimodal distributions of data with two peaks (one around 0 and the other around 1). I have provided an example of one of the distributions. Although their means and variances are different,...
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1answer
339 views

ARMA: modelling a time series with a bimodal distribution

I have a de-trended and de-seasonalized time series, and it's distribution is not gaussian (see distribution in Figure 1). I tried modelling it with and ARMA model, but as we could expect, this model ...
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1answer
31 views

How to sample/fit distribution from/for bi-modal data [closed]

The context is: I have a sequence of data, of which the histograms show a bi-modal pattern. My final goal is to sample from this sequence in a simulation project. Now we want to fit a parametric model ...
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1answer
545 views

How do I normalize a bimodal distribution?

I'm working with the Iris data.One of the variables,PetalWidth,Has a clear bimodal distribution My understanding is that Multivariate regression Assumes normality for each of the input variables Can ...
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1answer
325 views

Is this distribution bimodal? [duplicate]

so understanding what unimodal, bimodal & multimodal distributions mean was easy, but I wonder how strict should I be when I am applying the definitions to real data, in that sense, I need to ask, ...
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1answer
963 views

KS test for bimodal and unimodal distribution?

I am quite new to statistical tests and not sure how to exactly describe my question. I searched but could not find similar questions. Please do let me know if this is a redundant question. Thank you! ...
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1answer
47 views

How can I estimate the probability that my observed data come from a bimodal population?

I have a data set representing the abundance of a protein in a population of cells. Based on our understanding of the biology behind this, I expect there to be two subpopulations - one in which this ...
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5 views

Data set for mixed distribution - bimodel

I'm doing my undergraduate thesis and I need to have a data set which is distributed as bi-model in order to complete the application part. I'm going to use non- parametric methods to estimate the ...
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0answers
26 views

Theoretical reason for 1 linear model not being able to model a bimodal distribution?

Recently, I got a set of data where I try to predict the label (a continuous variable between 1000 - 3500) given 13 feature variables. By applying the kernel density approximation on the label (shown ...
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5 views

Bi-modal coefficient estimates of bootstrapped difference in differences estimate

I'm trying to conduct a sanity check on a really strange result I'm finding. I specified the following difference in differences logistic model in R: $Pass = \beta_{0} + \beta_{1}Attended\times\...
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0answers
45 views

Shared latent spaces

I have two interrelated response variables $A$ and $B$ over each observation $i$ in my data. I am trying to create an unsupervised model where observations could be explained by means of latent spaces(...
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0answers
11 views

How does the presence of multimodally distributed variable/ parameter effect my model?

I have come across this sentence many times - "All xs should come from same distribution'. I wanted to understand how will the presence of a multimodally distributed variable effect my modal. I have ...
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1answer
93 views

How to engineer a bimodal continuous feature for use in Decision Tree?

I have a predictor that exhibits "bimodal" behaviour. How can I engineer this feature to improve performance within a Decision Tree? For an intuitive example, consider how a binary flag of "moves ...
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0answers
80 views

How do I Identify a cutoff value from bimodal data?

I am putting together a regression model with data of carseat sales from the ISLR dataset. It is sales as a function of the independent variables. One of the variables has a bimodal distribution I ...
0
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1answer
58 views

Can I perform KMeans on a bimodal data?

I am preparing a dataset for KMean clusters. But a series of data appears to be bimodal: My question is: Can I perform KMeans on a bimodal data? If not, what kind ...
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29 views

Simulate a 2D-beta distribution: spatial simulations

I'm doing spatial simulations and I would like to simulate a matrix that represent a truncated 2D-bimodal distribution with U shape. In other words, I would expect high density towards the borders of ...