Questions tagged [frequency]

The frequency measures the number of times an event occurs in a data set.

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How to measure the period of an oscillation with least error?

I have a question about analyzing the data from a coupled pendulum. I have measured the amplitude $\psi(t)$ which is expected to be a beat and I want to measure the period. The ideal plot would be ...
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Statistics question related to the Charleston shooting

Note: This will be a long post, and I apologize for that. There's been a lot of parsing of President Obama's words with regards to the "frequency" of shootings in other countries. I contend he's ...
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Granger causality tests when series are measured at different frequencies

As a research exercise I should perform Granger causality tests on pairs of national series (one describing output gap and the other an index of consumers' confidence). However, I face a situation ...
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Probability of bad milk

Assume there are (always) $N$ bottles of milk on the grocery shelf. Each day, a deliveryman randomly selects a fixed $M \lt N$ bottles of milk from the shelf and replaces them with new bottles of milk....
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60 views

How do I compare frequency data of more than two groups?

I am comparing the frequencies of a disease presenting in particular season. The expected proportion would be 0.25 and the observed frequencies for spring, summer, autumn, and winter were 7, 9, 11, ...
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165 views

How to determine significant differences between frequency spectra?

I want to determine whether the mean of frequency spectra are statistically different from each other. I have a set of trials in different drug conditions and I want to test whether a drug had an ...
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218 views

Discrete Fourier Transform and uneven sampling

In this blog article an example is given of one can use the DFT to detect frequencies much higher than the sample rate. In the comments sections I asked how it was done, since DFT normally requires ...
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33 views

How to set the optimal value to a trigger signal?

I have an indicator which oscillates between -50 and +50 values. Then I have to set a optimal signal value to go long or short. I've thought in something like this: ...
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79 views

Modified German Tank problem involving string distance metrics

Pretend we have a list of items, e.g. names, and we know it is sorted ALPHANUMERICALLY let's say in ascending order. Given a small set of the first K items, how can we estimate the length of the full ...
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1answer
66 views

How to deal with frequencies that don't appear in the held-out set?

The held out probability is defined as $$P_{HO}\left(x\right)=\frac{t_{r}}{N_{r}\cdot\left|S^{H}\right|}$$ where: $t_{r}$ is the total number of times events that appeared $r$ times in the training ...
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166 views

Suggested algorithms for time series analysis of sporadic events

I have a series of sporadic, discrete time series events that appear to occur in shorter interval clusters and I am looking for a way to determine the frequencies at which the events occur. None of ...
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685 views

Chi-square on a categorical variables (derived from continuous distribution)

We know that Chi-Square can be used with categorical data (such as Male/Female, Republican/Democrat, etc). However, I convert my original continuous data to ...
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399 views

Frequency with repeated measures

I did an experiment in which I group objects based on machine learning. I then tested whether people group them in the same way. Each subject (I had 30 subjects) watches 8 sets of 3 objects. In each ...
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1answer
102 views

Is there a better term for frequency distribution of a term frequency?

I am wondering if there is a better way of formulating this and also if this is a correct way of formulating it. What I'm trying to represent in the frequency distribution is the count of documents ...
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52 views

Generalization of skewness detection in non-uniform case

I am not sure if my title reflects what I am attempting to ask. Let me elaborate my question. I want to classify an observation/feature into one of two categories ($A$ and $B$) based on frequency of ...
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1answer
263 views

Is Rule of Three inappropriate in some cases?

I'm building binomial proportion confidence intervals for a patient dataset containing the frequency of home nursing visits during the week prior to hospital admission. The freq. of home visit ...
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481 views

On the uniform convergence of relative frequencies of events to their probabilities

I have read the article by Vapnik, Chervonenkis "On the uniform convergence of relative frequencies of events to their probabilities" Theory of Probability and Its Applications, vol XVI, n. , 1971. ...
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Comparing frequencies in two groups between two time periods

I've got data that are essentially set up in two 2x2 frequency tables. I have frequencies that males and females disperse or recruit to a given region. I am interested if the proportion of sexes that ...
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34 views

Specification on power spectral density for population data

What is the best way to put a specification on the single-side auto-power spectral density (PSD)? We have a product for which we have a time signal. For this signal we calculate the PSD (or ...
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Cepstrum: quefrency scale to frequency scale

Can someone please explain to me how to convert a quefrency scale to the corresponding freqncy? For example consider this: A voice signal is measured at 50kHz sampling frequency and FFT power ...
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34 views

Statistical analysis for quasi-experiments

This is my first message on this forum. I hope I am not doing any mistake. I must analyze data obtained after a quasi-experiment and I am not sure how to proceed. The experiment has been carried out ...
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44 views

Should I use weekly or daily returns for modelling FX returns?

I am currently modelling Foreingn Exchange returns using a GARCH model. I am simulating returns 1-year forward. Would it be better to use weekly or daily data on Foreign Exchange returns? Weekly data ...
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33 views

Fisher's exact test with opposite direction of categories for two groups

I would like to analyze student performance under two teaching approaches for two classes. We predict that class 1 would outperform class 2 and ideally the performance between two classes should be ...
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39 views

How to analyze the frequency of correct/ non-correct answers

I have a question about how to analyze some data. It involves the performance of two equally sized groups in a questionary with 30 arithmetic questions that I scored with two possible outcomes (...
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calculating sample size needed for a target confidence interval from categorical data

So I will have data sorted into one of five bins (flow cytometry sorting of cells). These bins are actually adjacent categories that quantify a single fluorscence level (0-20,20-40,40-60,60-80,80-100)....
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Relative frequency question

I am a new user here, and I need some help getting started with the following question: The textbook answers are a. $19$ and b. $20$. How do I begin this question? I am a beginner in statistics. :) ...
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How to analyze size frequency data from over 70 sites

When I started my PhD, I had virtually no prep-time. My advisor needed me in the field and told me to go grab samples. As such, my planning wasn't the best, so sorry if this is a completely terrible ...
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92 views

Estimating standard deviation from cumulative frequency table

I've been provided with some data in the form of a cumulative frequency table, where each value is exceeded a qiven percentage of the time, so for 99% of the time the readings exceed 163 and for 1% of ...
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2answers
46 views

Frequency of an event at a given time, from a list of times of occurrence

I have data in the following format: [$t_1, t_2, t_3, \dots, t_n$] - which is a list of times at which an event has occurred during a day They are in minutes within 24 hours and limited by $t_{\text ...
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50 views

Compare frequencies/proportions across groups which may overlap with one another

Let's say I want to compare the recurrence rate of a house that is on fire/flooded/robbed this year will be on fire/flooded/robbed the next year in a neighborhood. My data look like this: ...
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52 views

creating frequency table

I have empirical data from what I am trying to produce frequency table. when I use table for showing frequency result is ...
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49 views

On data granularity involving PCA

So I have a very large amount of data, on a 15 minute frequency. I want to reduce dimensionality, so PCA seems like a good choice. However, there's a catch -- I will use monthly data, not 15 minutes. ...
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33 views

Periodicity in noisy data and the usefulness of differencing

Disclaimer: I don't have great stats knowledge. I'm doing some exploratory data analysis with the goal of detecting whether or not there is periodicity in the data set. I have a collection of photon ...
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1answer
55 views

What is the frequency range for a discrete time series?

We're covering spectral analysis for discrete time stationary processes in lectures, and I can't really get my head around something which seemingly should be easy. "Because time is discrete, we only ...
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23 views

How often we expect an event to occur in a given year regardless of location?

I'm trying to determine how often an event will occur in a given year regardless of location and determine a 95% confidence interval. I have the year, location, and how often it occur for the given ...
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52 views

How to measure a mean frequence of fft transform

I have this time series (utilization of app by day of an user) And this fourier transform of the above time series How can I extract one number that express the mean frequency of this time series? ...
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58 views

How are various rules for determining frequency distribution binwidth derived?

I've been looking up the problem of deciding appropriate binwidths for histograms and here's my broad-level understanding so far: If we have $n$ data points, we assume that they're realizations of $n$...
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308 views

PLS regression - My X and Y blocks are obtained at different sampling frequencies. Should I trim the X block or smooth and interpolate the Y block?

PLS (partial least squares) regression is the tool that I'm using to express each Y block variable as a linear function of the X block variables. The overall goal of this project is to create a model ...
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202 views

detecting change point in the time series on a 2 dimensional space

I have a 2 dimensional geographic space. There are crime events occuring at different regions in the space over time. I am looking particularly at property crimes like burglary. If I look at the time ...
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34 views

statistical test to see which type is the most frequent in each group

I have four groups of speakers, and I have the count of verbs, adjectives, nouns, and adverbs per each individual in each group. I would like to see which of these grammatical type is the most ...
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Is T Test the proper method to compare two character frequency tables?

Given two sets of histogram both arranged alphabetically: [ A ] containing the typical frequency of letters in the English language [ B ] containing the frequency of letters in this cryptogram (...
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685 views

p-values from frequency table?

I am doing a data science practice project, seeing if there is any correlation between crime and moon phase. I have created some frequency tables of crime numbers along with moon phase and it looks ...
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129 views

Why is the Haar wavelet providing better frequency discrimination than alternatives?

I'm using PyWavelets (aka "pywt") to understand the discrete wavelet transform, and I'm trying to construct a crude power spectrum of a sinusoidal time series with frequency components of 1/8 and 1/32....
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How to interpret frequency decomposition of a time series?

Consider a time-series $x_t$ at, say, quarterly frequency. I perform a discrete Fourier transform (DFT) $z(f)$ of $x_t$. Then, for each $z(f)$ I perform the inverse transform and get $x_t(f)$, that ...
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Can I Use DFT To Find The Most Common Frequency?

I have a collection of data which measures the change in state of a device which records information. I basically record the time a new observation is made on the device. I want to collect the data ...
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1answer
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Enrichment of mutations in particular region of the gene

I have a gene say "X" of 3000 base pairs. 300 of those 3000 bp belong to ring domain. Rest 2700 do not belong to ring domain. In a particular tumor, the ring region has 4 alterations and the rest of ...
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Estimating the distribution of frequencies from a sampling of unique values

Let $L$ be a list of elements with repetitions, and $S$ be the set of elements appearing in $L$. I have two tools at my disposal: I have a sample of $k$ elements taken uniformly in $S$, and for each ...
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test significance for frequencies

I have frequency data for six datasets (3 control samples and 3 treated samples) consisting of values for physical stiffness, when I plot the frequencies against stiffness it looks like the treated ...
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Inference of frequency of values in a poisson distributed histogram

For some data there is a histogram, which has bins with varying sizes. Is it possible to infer the frequency of the values for smaller segments of the bins, favourably with Matlab? With the attached ...
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Differences in variables constructed by counting.

I have constructed a frequency variable from counting events of certain magnitude (e.g, 1,2,3...) from a time dependent experiment with animals. I have two groups (Trained vs Control) and two phases ...