Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

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..

A bimodal distribution can arise as a mixture of two different unimodal distributions (i.e. distributions having only one mode). In other words, the bimodally distributed random variable X is defined as $Y$ with probability $\alpha$ or $Z$ with probability $(1-\alpha)$, where $Y$ and $Z$ are unimodal random variables and $0 <\alpha <1$ is a mixture coefficient.

Below is an example of a bimodal distribution:

enter image description here

When the two modes are unequal the larger mode is known as the major mode and the other as the minor mode.

-- Wikipedia

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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 program?
Pauloc
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Why is a mixture of two normally distributed variables only bimodal if their means differ by at least two times the common standard deviation?

Under mixture of two normal distributions: https://en.wikipedia.org/wiki/Multimodal_distribution#Mixture_of_two_normal_distributions "A mixture of two normal distributions has five parameters to estimate: the two means, the two variances and the…
M Waz
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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-statistic is bimodal in distribution? does…
Alby
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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 get a bimodal distribution when bootstrapping (see…
Valentin
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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 found this source, which helps to simulate a…
deschen
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How is a Bimodal distribution platykurtic?

I am trying to understand how the distribution on the right is platykurtic? I learned that platykurtic indicates lighter and thinner tails and from what it looks like, the bimodal distribution, with a superimposed normal curve, seems to have a lot…
cf8261a
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Is there an estimator for the symmetry of a 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?
alexi
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How to interpret histogram and normaltest result?

I investigated dataset using histogram and normaltest. I used scipy.stats.normaltest, got this result: NormaltestResult(statistic=5.6921385593741958, pvalue=0.058072138171599869) The p-value is slightly larger than 0.05, which means it is normal…
planaria
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How do I normalize a bimodal distribution?

I'm working with the Iris dataset. One of the variables, PetalWidth, has a clear bimodal distribution. My understanding is that multivariate regression sssumes normality for each of the input variables. Can I continue with the variable left alone?…
Sebastian
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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 from a panel of judges. I have a theory that a…
AmourK
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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 to model p(x=1) vs p(x=0). I mean the target…
user133248
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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-smooth regions? what about tri-modal? I have discrete…
cmo
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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 ?
the_dude
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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) where respondents have been randomized into three…
Persson_Sweden
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Can I do a hypothesis test to see if two populations are different if there are known subpopulations within the data?

I have a continuously variable output (diffusivities) that I have measured from two different populations (say "Case 1" and "Case 2"), and I am trying to see if the two populations are different. The trouble is, each population has two known…
thedu
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