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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Fisher Information for frequency estimation under non-circular complex Gaussian noise
Consider a non-circular complex Gaussian noise $v$, which is given as $v = v_r + iv_i$. Here, real and imaginary components are independent and are Normal random variables such as $v_r \sim \mathcal{N}...
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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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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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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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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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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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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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Power for hierarchical loglinear model
Can anyone point me in the right direction for doing sample size/power calculations for hierarchical log-linear analysis of nominal (frequencies) data? Would I get in trouble with reviewers for just ...
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What test to compare two frequencies?
In my project I have to study the vigilance behaviour of birds, and I need to determine if adults start escaping from an approaching human more often than chicks. So I have the frequencies of adults ...
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How to assess if a distribution has significantly changed over time
I'm studying the incidence of different types of influenza in a country over several years. In particular, for years from 2015 to 2020 I know the relative abundance of 3 types of influenza (% of ...
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Derive summary statistic Grouped Data & Frequency Distribution Table
I have the following data from the 2018 American Community Survey for a number of census block groups:
...
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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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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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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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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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What do you think is the right tooling to separate sub-time series from a single big time series?
I would like to separate a big time series into its components to improve forecasting.
To clarify: I would like to find the different components - maybe it is better to say frequencies which ...
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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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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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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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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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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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Can we apply a permutation test to compare two percentage distributions?
Any help here will be greatly appreciated!
Suppose we have two groups, one composed of ET's from Mars and another from ET's from Jupiter (assuming there are ETs there).
Then, these groups of ETs meet ...
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What type of statistical test can I use to look at the influence of a factor on a frequency distribution (distance)
I'm trying to work out what test to use to see whether a factor (presence vs absence) affects a frequency distribution with distance as a predictor.
Just wondering if anyone knows what the best test ...
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processing natural language that descripe time frequency with R
I'm dealing with data that descripe onset frequency of a symptom. The text in each cell was not in the same format. For example:
...
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Time Series Seasonality and Frequency
I am working with a time series that indicates the number of times a user logs into an application per minute. I want to find an algorithmic way (in Python) that would detect if there is any pattern ...
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Scientific reporting of time-varying covariates at different time frequencies
Say I have the following model:
$$y_{it} = \gamma_i + \delta {T}_{it} + \zeta Z_{i(k)} + \epsilon_{it}$$
where $y$ is some outcome for household $i$ in month $t$. $\gamma_i$ denotes household fixed ...
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Likelihood that observed relative frequencies match a probability distribution
For this question, please assume probability distributions are discrete.
If I have $N$ data points ($x_1, x_2, ..., x_N$), and I want to know the likelihood that these samples came from a discrete ...
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Dealing with zero cells in the psi frequency test
In Jayne's "Theory of Probability" book, he proposes the psi test of frequency as opposed to the more common chi-squared test. He demonstrates how the test deals better with low-expected ...
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Standard Notion of Limit for relative frequency to define probability
I am self studying probability theory and am reading the book:
Understanding Probability: Chance Rules in Everyday Life by Henk Tijms.
In second chapter he explains about what challenges relative ...
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Relation between Fourier transforms and coherence of signals
My overall aim is to compare the edges of two images by comparing their Fourier Transforms (FFT) and to calculate one number as a key performance indicator that describes how much they are similar to ...
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How to convert high to low frequency data
I have data for a macroeconomic variable, and it has monthly frequency but I need to work with it in quarters. Is there a statistical method to perform this frequency conversion that ensures the least ...
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How best to display skewed frequency data?
I am counting the number of eggs laid each day by some animals. Most days under my experimental conditions, individuals produce 0 eggs (194/307 observations). I do not want to leave these 0 days out ...
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How do I deal with nonexistant data in an irregular frequency time series?
I am trying to do some time series analysis on the margin resulting from three specific commodity futures contracts and ultimately forecast the margin. The margin is calculated as M = F1 + F2 - F3. I ...
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Assessing the fit of a distribution of absolute frequencies to a distribution of relative frequencies
Problem: From a related paper, we have a distribution of relative frequencies for a set of actions people do when working with a particular tool. In a study of our own, we measured a set of absolute ...
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Comparing the significance of multiple group frequencies in R
Suppose I have sum of frequencies from 4 groups with:
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How to calculate similarities/distances and conduct cluster analysis from contingency table
I have an 18x25 contingency matrix, rows are behaviors observed and columns are environmental features. I conducted a correspondence analysis via the CA() function in R and then clustered using the ...
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How to identify the frequencies of periodic peak signals in a noisy time series? (with R)
Suppose to have two time series with peak signals at different frequencies, like these two:
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What is the Frequency Modulation (FM) Synthesis formula?
I am very confused with the FM synthesis formula
I had summarize below in a Latex (because I do not know how to type all the fomular here)
But whey all the formula is different?
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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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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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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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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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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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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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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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