Time series are data observed over time (either in continuous time or at discrete time periods).

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is it possible a nonstationary time series, to produce a stationary ARMA model?

I Have a variable (time series) which is nonstationary. I found that from the graph which seems to have a stochastic trend and the correlogram has a typical nonstationary pattern. After that, I've ...
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How do I investigate how long it takes one variable to affect another in a time series

I am a total newbie when it comes to time series, so it is quite possible this question is duplicated somewhere else, only that I cannot find it because I don't know what this feature is called. My ...
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1answer
22 views

Filtering using a SARIMA model in R

I am not an expert in statistics, but I would like to work on a SARIMAX model representing power consumption. The exogeneous variable would be the temperature, but for now I found here I might need to ...
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25 views

Where can I find resources to learn about change-point analysis ?

Where can I find resources to learn about change-point analysis ? Hopefully, someone can advise me a textbook to read and it will cover both univariate change-point analysis and multivariate ...
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ACF and PACF plot analysis

I am new to ARIMA, and I am trying to understand these lag plots. Are the following ACF and PACF suggesting that the lag of my time series is 4? If I am wrong, please help me understand these plots. ...
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21 views

Arima model - multi step forecast

The following code shows a forecast of the next 24 hours of my electricity prices with two exogenous variables. My problem is, that I don't know how to build a forecast for the next 3 days or more ...
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19 views

Holt Winters Initialization Issue

I am using an additive seasonal Holt-Winters model to compute confidence band of my data. I followed the HW initialization process described by Rob J Hyn­d­man. The confidence band is derived by ...
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2answers
61 views

Capturing Seasonality in Multiple Regression for daily data

I have a daily sales data for a product which is highly seasonal. I want to capture the seasonality in the regression model. How I can do it? I have read that if you have quarterly or monthly data, in ...
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31 views

Two or more time series. What is the best way to test whether one of them is leading and by what time period?

I am trying to prove/disprove that one time series is leading trend for the other ones. Two time series are (probably) independent and the movements are caused by some (let's assume unknown) common ...
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8 views

References suggested for multivariate analysis of several similar time series

I have a time series dataset that reports the hourly page views and social media shares of online news stories. What I hope to obtain is the relationship between the two variables. I would imagine ...
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17 views

Searching for time series inside another time series

I have a time series "A" and another one "B". I would like to find occurrences of "B" inside "A". Typically, "A" is much bigger (magnitude: millions of points) than "B" (magnitude: hundreds of points) ...
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Is this the proper way to create a simple linear time series model in R

I'm trying to create a simple ols model over time from a time series. Here's what I have cagr.lm.time <- lm(cagr.xts ~ time(cagr.xts)) Where cagr.xts is the ...
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22 views

Evaluating the temporal corelation model for which the differencing is performed for trend removing

According to the literature, for temporal correlation modeling the trend should be removed from the time-series data. We choose differencing for removing the trend. I would like to know: When we ...
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1answer
12 views

Quantifying Change in a Histogram Valued Timeseries

I'm attempting to do binary classification where my raw features are collections of histograms that are recorded in a time series. These histograms are scaled to sum to 1. To be more precise and ...
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5 views

Standard deviation of multiple root mean square values

I am calculating the R.M.S. of a periodic signal that has a stochastic component to it. For every period I am able to calculate a value for R.M.S. using the following function: $R.M.S. = ...
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If two time series $X$ and $Z$ follow $0 \leq Z \leq X$, can we say that $\text{var}(Z) \leq \text{var}(X)$?

Now I see it can't hold. Thank you for the counter examples... You guys rule! Thank you very much for your comments! I added, however, some observations that were missing. Most importantly is the ...
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1answer
50 views
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R: Fitting a model with periodic, nonlinear and categorical components

Can anyone give me some advice on how to fit a model with linear (some categorical), non-linear and time series components in R? I don't want to use a non-parametric model like a Loess smooth or ...
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18 views

Mann-Kendall test STATA

I am new in this forum. I am beginning to work with time series, I have a daily (25,000+ observations) temperature dataset (01/01/1946 - 07/01/2014) I want to test for the following: Trends: So ...
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22 views

Forecasting time series with missing data and irregular intervals

I have a data set of medical drug stock levels at health centres and I want to forecast monthly consumption over the following 3-6 months. However about 30%-40% of the data is missing and some of the ...
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1answer
23 views

MAPE is high for daily sale prediction

I have daily sales data from 2011 to 2013. I have to do prediction for 2014.I have used arima and exponential method to predict the daily sale, but it is not giving the better result. MAPE is around ...
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1answer
17 views

Getting expected value of future value with time varying data (credit card revolving and fee data) . Customer lifetime value

I have a credit card data and that contains monthly amount of revolving and amount of fee for each customer. As a bank perspective, I want to get the expected value of future revolving amount and fee ...
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39 views

Calculate the average of hourly data of three sensors

I am trying to calculate the average of hourly data of three sensors but the hourly timestamps of all three sensors are different. How is it possible to measure the average of hourly data of all three ...
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13 views

Are there any time-series visualization tools available for HDF5 files?

I have gigabytes of time-series data stored in HDF5 files and while there is the very basic visualization tool available in HDFViewer, I'm interested in knowing if there are rich visualization ...
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34 views

How to perform proper data mining on time-series data?

I have some daily data from city A, B, C. Values from city A are highly correlated with values from other cities for lag -1,-2,-3 and -4. I want to use Random Forest, SVM and ANN to predict values ...
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209 views

Is there a statistical measure for how much a variable fluctuates over time?

Is there a statistical measure for how much a variable fluctuates over time? For example a noise signal fluctuates a lot. However, if you would sort all values of the signal in time, you would have a ...
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1answer
32 views

Time Series Data Mining Library?

Can anyone recommend a library for time series data mining tasks other than predictive modeling and statistical analysis? There seem to be a number for these purposes (e.g., Gretl), but nothing for ...
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1answer
19 views

Can I difference after fitting a time series regression model?

Suppose that I have a time series that exhibits a notable trend, and I want to test a hypothesis that a second variable is related to that trend. I fit a linear regression model with that second ...
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23 views

ets() or stlf()

Every where I read, experts suggested to use ets() to better determine alpha, beta, gamma ...
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1answer
34 views

How to compare difference between two time series?

I am working on my thesis where I'm examining how strong emotion people show to different events. My problem is (1) that I have VERY little experience with statistics and math, so I'm kind of lost ...
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29 views

Forecasting agricultural commodity prices with R

I would like to create a predictive model in order to forecast the price of an agricultural raw material. I got time series for the prices and the production of this raw material, and also for the ...
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10 views

Derive minimum positive rate of change for co2 data

I have CO2 (in parts per million) data of a closed room. The CO2 data is recorded along with timestamps. Typical difference between two samples is around five minutes. My aim is to find occupancy of ...
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1answer
33 views

Given time series data, how to model the frequency of someone changes his job?

I am given a time series data vector (ordered by months and years),which contains only 0s and 1s. ...
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12 views

Testing for heteroskedasticity of time series in R

I wish to test my time series data for volatility clustering, i.e. conditional heteroskedasticity. So far, I have used the ACF test on the squared and absolute returns of my data, as well as the ...
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1answer
22 views

ARIMA modeling with more than one Categorical Variable

I am using auto.arima for forecasting. I have more than one categorical variables having more than one level. My questions are : Do I need to do dummy coding ? ...
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11 views

dynamic probit model

I want to know if you can helpme I have a binaray response yt take values 1,0 and a covariate Xt continua and I have to estimate the parameters of the model using maximun likelihood method ...
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9 views

Pattern and most influential parameter detection.

I need some advise to approach the solution. Here is the question. Background: The growth of bacteria, Gb is dependant on 4 factors W, X, Y, Z where W and X --- can take any integer value from -10 ...
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24 views

Interaction in time series analysis

I have three different physiological variables--heart rate, respiratory rate and blood oxygen saturation, each as a time series. I am trying to study the interaction between the variables as they ...
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19 views

How to approach time series regression with one continuous variable and one “ almost Boolean” variable?

I am working in R with daily time series data and have daily observations of two variables. The first is continuous. The second is zero for every day except one, in which it is a number (I'm not sure ...
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1answer
15 views

Stationarity consideration in ARIMA using KPSS test

I have data, which I am sure has a downward trend. I am trying to forecast this data using ARIMA and I want ARIMA to consider the trend when it is forecasting. The first step in ARIMA is to ...
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70 views

Time series with negative data in R [on hold]

I have data for forecasting like, here negative value is actual data ...
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Tail index using hill estimator in R [migrated]

As part of my data analysis (of heavy-tailed data) I wish to calculate the tail (for both left and right) indices of around 100 time series of company returns. My data is stored in a large zoo object, ...
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56 views

Intervention Analysis Coding in R TSA Package

I am studying intervention analysis in time series with the Cryer and Chan book and am looking at trying to understand how to code the step response interventions. One question I had is how to ...
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9 views

Correlation between variables over time

I have two variables over two different years. Week by week pageview numbers in 2013 and 2014 and week by week # of posts in 2013 and 2014 (number of articles posted). I'm trying to find out if ...
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15 views

Outlier treatment in Vector Autoregression (VAR) Model using vars package in r

I have the same problem as the following post, but I have more samples and the index of the outlier is known. Outlier treatment in Vector Autoregression (VAR) Model I tried deleting the outliers; ...
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24 views

Demand Forecasting : Montecarlo Simulation

I am trying to build a demand forecasting model for human resource team. I have thought of using monte carlo simulation method to do it. Is it the right technique for it? Has anyone used it to ...
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58 views

F-statistic value is too high for my model

Number of obs = 501 , Method: Fixed-effects regression Number of groups = 101 F( 10, 100) = 3422.31 , Prob > F = 0.0000 , ...
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1answer
52 views

Backshift operator property not clear

In my introductory book on time series analysis the backshift operator $\mathbf{B}$ is introduced using the following definition: $$ \mathbf{B}x_t=x_{t-1} $$ Then the author sets off to derive some ...
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26 views

Bayesian method for computing credibility interval for correlated time series

I'm studying a stochastic process generated by simulation using two different methods. In the first, the waiting time between events can be shown to be exponentially distributed. To model the ...
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29 views

Can seasonality be detected / explored with principal components analysis?

I have a rainfall data consisting of around 95 years for the rows and twelve months of the year for columns. So this is a 95x12 matrix, not a column vector. Can I derive any idea about the months to ...
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104 views

Question with MLE

I'm having some problems with this question, and was hoping someone here could help. Let $X_1,\ldots,X_2$ be $n$ determinations of a physical constant $\theta$. Consider the model $X_i = ...