# Tagged Questions

A histogram is a graphical representation of the frequencies of a continuous variable. The variable is divided into bins and a bar is drawn for each bin, proportional to its frequency in the data.

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### Is this close enough to be normally distributed for using a parametric test?

Can I say that the values are close enough to be normally distributed? The histogram does not look normally distributed at all, but the Q-Q plot is not so far away. My sample size is 30. The shapiro-...
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### Sequential update of probability value from Histogram

Given some observation $\mathbf{x}_{i}$ of some random variable $X$ and a histogram model $H$ over $X$, the probability of the observation given the distribution $H$ is given by $P(\mathbf{x_{i}} | H)$...
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### Bag of Features: why the distance between two histograms of the same image is different than 0?

I'm trying to implement a Content Based Image Retrieval application for small image datasets. I'm testing it just with 1 thousands images from Caltech1001. The approach that I'm using is the classic ...
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### Why should we normalize Bag of Features histograms?

I was reading these slides about Bag of Features (BoF). At slide 23 you can read: each image is represented by a vector, typically 1000-4000 dimension, normalization with L1/L2 norm Why we ...
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### 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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### How do I quantify the uniformity of sampling time?

My datasets cover a long time, say 20 years, and the data are sampled at different time. For example, some are obtaiend at 1:00(stored as 100), some are 23:00(2300). If I plot the histogram of the ...
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### Permutation testing to check statistical significance of 2D distribution

I have a bunch of 2D distribution/histograms that represent variable X against variable Y, across several conditions. The histograms look something like: For each condition (each data summary as ...
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### Obtaining distribution from histogram

I have an array of values, with those values I plotted the histogram, calculated mean and variance. I want to know the corresponding distribution from the histogram obtained. How is it possible? Could ...
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### How to best describe a bunch of 2D histograms/distributions?

For chords of several music genres, I have subjective ratings from subjects that show how pleasant they found each chord (x axis below) and also how consonant (y axis). A scatter plot (or rather a ...
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### Proper way of averaging histograms

How does one go about averaging multiple histograms of a quantity $x,$ if the individual histograms do not have the same range, that is, $R_i=\text{max}(x_i)-\text{min}(x_i)$ will be different for two ...
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### Interpretation in histogram of empirical posterior distribution

I'm having trouble to understand the following histograms I know that the posterior distribution in this case is just the empirical cumulative P(\rho\leq c)=\frac{1}{n}\sum_{i=1}^n \mathbb{...
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### How to compute the firing rate of a neuron with different duration of trials?

I have recorded data from a neuron from different trials. Each trial we show a stimulus to a rat and then we measure the neural activity. I want to measure the PSTH which is peristimulus time ...
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### repetitive values

I have a data table that looks like this: USER AREA 1 X723 1 X278 2 X827 2 X567 2 X234 3 X735 3 X673 3 X346 4 X723 5 X678 Then I converted ...
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### What is the purpose of multiplying by the difference between the midpoints of two bins in this recipe?

While browsing for information on how I might plot a fitted normal curve over a histogram, I found the following: http://www.statmethods.net/graphs/density.html There is a line I don't fully ...
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### Calculating uncertainties for histogram bins of experimental data with known measurement errors

I have a set of experimental data (with each data-point having its own measured uncertainty), and I wish to produce a histogram of it. The x values of the edges of each bin are already defined. The ...
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### Can you test for normality for a (0,1) bounded distribution?

I have a vector of observations called MyData which is a percentile score that is >= 0 and <= 1. I would like to test the ...
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### Histogram bin size to show deviation from uniform distribution

Simple question: Is there a rule of thumb for number of bins in a histogram with a uniform distribution? Details: I have a stochastic computer simulation that produces, as a test, $n$ values that ...
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### Which search algo I should use to find simmilar histograms inside my huge database?

I'have a huge database of about 10^8 objects. Every object contains max. 500 words from a dictionary with 50000 words (BoW). An object from my database could look ...
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### Is this histogram normally distributed?

Is this histogram normally distributed? I can't tell since there are peaks that are outside the curve.
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### What is the name for the distribution shape of a histogram with this kind of curvature?

I have a histogram of points with a dip in the center of the bell, seeming to create two bells, or two clusters. What is the name for this kind of shaped distribution? This curve should be normal but ...
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### How to determine the similarity between histograms

The questions is asked at How to assess the similarity of two histograms? However, I'm not sure if it's the same question as mine, so I'd like to ask again. I have a dataset, which covers a long ...
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### How to better plot and compare overlapping histograms?

I want to compare the distribution of 3 different time spans: So I plot the histograms together, along with the model curve. But I'm afraid that overlapping histograms makes each hard to see. The ...
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### Figuring out distribution parameters for specified modes

I'm trying to find out, which parameters $\alpha_i$ should Dirichlet distribution have in order to have as modes some specified $x_i$. The formula for mode for Dirichlet distribution is this (from ...
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### How do we normalize a set of histograms?

I have 100 histograms which have different (min,max) ranges. Each histogram is of 127 bins. What is the procedure ti normalize these histogram? Need help...
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### Reference for known issues with histograms (binning, anchor point)

I'm looking for references on the known issues that arise when working with histograms, i.e.: the choice of the number of bins, and the choice of the origin point. The WP entry on Multivariate kernel ...
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### Comparing count groups/hisotgrams with different bins

I'm looking at clustering techinques for which I have a ground truth. From the ground truth I can extract the cardinality (size) of clusters and I would like to test how well different methods can ...
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### Bird eye view of unknown data set [duplicate]

Pardon me if this question does not fit this site (or SE engine in general) but I do not know where to post it. Suppose that you have unknown data set which you want to explore. What functions/methods/...
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### I need help to determine the distribution

So I have an assignment to estimate the distribution of different sets of and then make a goodfit test to see if the assumption is correct. This is my current histogram, and I have tried both ...
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### Verifying that a random generator outputs a uniform distribution

I asked a student of mine this question: If you have a random number generator that outputs a number between $1$ and $k$, how would you write a test that decides whether the generated ...
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### Why aren't bivariate histogram matrices as common as scatter plot matrices

Bivariate histogram matrices give me intuition which categorical variables are related to one another. For example: I can easily see which variables are related to one another. Indeed, this ...
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### Transformation of specific data

I need help with data transformation. In the picture below the upper left picture shows the histogram of the variable V6. Because it is so right-skewed I tried 3 forms of transformation but none of ...
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### What information does a Box Plot provide that a Histogram does not?

Histograms give a good sense of the distribution of a variable. Box plots attempt to do the same thing however, don't give as good of a picture of the distribution of this variable. I don't ...
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### What kind of distribution is this? Many trials and guess the distributions for different settings

I've plotted the histogram of the number of stones required so that 2 are adjacent when randomly placed 1 by 1 on a goban (think of a 19x19 chessboard and I place pieces 1 by 1 until 2 are adjacent, ...
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### Evaluation of a group of histograms

I'm trying to learn statistics on my own and currently taking an online class through edX. Unfortunately some things are not clearly explained. The online book used for this class contains the ...
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### Error of empirical probability for unfair die

I roll an unfair $256$-sided die $n$ times ($n > 1'000'000$) and count the rolled numbers in a histogram. I then calculate the empirical probabilities ${p_e}_i$ for $i=1, ..., 256$ by taking the ...
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### Fit a function f on dataset X such that f(X) fits a histogram

I have dataset $X=\{\boldsymbol{x_1},\boldsymbol{x_2},\dots,\boldsymbol{x_n}\}$ and $Y=\{y_1,y_2,\dots,y_n\}$ and want to learn a function $f$ such that $y = f(\boldsymbol{x})$ can be approximated as ...
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### How to apply distance metrics to compare bar plot (nominal histogram) data

I have a data set for libraries, I would like to find the (Similarity / dissimilarity) among it based on book category, so for each category there is single value represent the number of books that ...
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### Why are there lines in my scatterplot: regression standardized predicted value -regression standardized residual [duplicate]

I used SPPS for creating this scatterplot,I made it like this: analyze â€“ regression- linear â€“ plots: y: ZRESID en bij X: ZPRED The dependent variable is social anxiety The independent variables are ...
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### inequal amplitudes and opened classes

i have to questions and i need the help of experts 1)In the case of inequal amplitudes, is the sum of the corrected frequencies is equal to unit? 2)In the case where the extreme classes are opened , ...
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### How to find a linear dependency in a 2-D histogram?

I have a matrix (average of several trials), with x and y as independent variables, and z as dependent variable. It can be plotted as a 2-D histogram. Now I want to detect if there is any significant ...
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### how to measure similarity of two lists of continuous data with different length

I have two lists of continuous data with different length. a) How should I measure (dis)similarity of these two lists? or, as these lists can be formed into histogram, how can I quantify (dis)...
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### which classifier to choose for probability histogram-like features

I have a populations of 500 elements. Each element is represented by a 10 dimension feature vector which sum of element is equal to 1 (you can think about it as a histogram of probabilities). In ...
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### Quantization threshold selection

I have the 256-bin histogram representing a distribution of the values taken by a certain descriptor element. This descriptor element takes the values in 0-255 range, hence 256 bins. I want to ...
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### Paired t-test vs Wilcoxon signed rank

I conducted a pilot study (n=14) which was evaluated retrospectively. I have four parameters with a pre-intervention and post-intervention score that I want to compare. I am wondering whether I can do ...
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### Sample from distribution given by histogram

Given a histogram obtained using given data points, how do I randomly sample from the distribution predicted by the histogram? Any conceptual comment / R code would be welcome.
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### Computing 'histogram' similarity when the elements can be positively or negatively weighted

The 'histograms' I want to compare may have positive or negative bin-values. I use the quotes because I am not sure histogram is the correct name. The elements that are being sample have associated ...
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### What kind of distribution is my QQ-plot and histogram?

I am pretty in new in distribution issues and I am trying to figure out what kind of distribution I have. I have a historical data with more than 300 observations. I will calculate Value-at-Risk (VaR)...
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### Non parametric density estimation

In general it's possible to estimate a given multivariate density function $f(x)$ using some non-parametric methods such as kernels or histogram. What are the conditions on a function $g$ such that ...