# Questions tagged [time-series]

statistical techniques for application to data whose observations concern an entity or phenomenon at different points in time.

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### Deriving ADF unit root test form for the time series with quadratic deterministic trend

I have the following time series process $y_t$ $$\Delta y_t = \delta + \gamma t + \epsilon_t$$ where $e_t$ is white noise process with the variance of $\sigma^2$. I guess that whereas $\Delta y_t$ is ...
• 334
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### Application of Maximum Likelihood estimation (MLE) to the Generalized Least Square (GLS) model

I have the following regression $$y = X\beta +u$$ where $y$ and $u$ are $(n\times 1)$ and $X$ is a fixed $(n \times k)$ matrix with full column rank and $\beta$ is an unknown $(k\times 1)$ vector of ...
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1 vote
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### The effect of stationarity of forecasting

If all that matters in forecasting is getting an accurate forecast then why is using non stationary data a problem. Say you use non stationary data to create a forecast that performs well in a pseudo ...
19 views

### How can I say if a variable Granger-causes another variable in a VEC model?

If I have a VEC model output with coefficients and associated standard errors, how I can say if a variable Granger-causes another one by just looking at the output and without any test?
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### Is there some standard way to diagnose a structural time series model (also called simple unobserved components model)?

I am dealing with a structural time series model (also called simple unobserved components model), and I wonder if there is some standard way to diagnose this sort of models. In most reference books ...
• 101
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### How to assess the quality of a forecast?

Let's say I have a time series model (VAR model for example). How can I know that my forecast is good ? I could use the R2 but is there something else? I also know I could just use in sample ...
• 437
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### Which variable keep/get rid in a time series model?

Let s say I have a big VAR model with many variables. Then I run the model. How can I know which variables I should keep or get rid of if I want to ameliorate my model ? What if my model has so many ...
• 437
24 views

### can someone help to interpret ACF and PACF graph?

can someone help to interpret ACF and PACF graph? in the graphs, I don't see any decay. am I right about that assumption other than that what can I comment about both? the data plotted is squared ...
1 vote
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### Is there granger causality that can be applied to panel data with structural breaks?

I have panel data containing various macroeconomic variables (for example: interest rate, output, unemployment). I would like to run a Granger causality test on some of them, but there are structural ...
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### A conceptual question about the limitation of the MA processes

We know that linear time-series techniques are frequently used in macroeconometrics. The Wold Representation Theorem states that any covariance-stationary process may be expressed as an MA process ...
• 121
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### Proof that a Unit Root process is Difference Stationary

Consider $$y_t =a_1 y_{t-1}+a_2 y_{t-2} +...+a_p y_{t-p} +\varepsilon_t$$ The characteristic polynomial would be: $$(1-a_1L -a_2L^2 -...-a_pL^p)$$ Suppose that there is a unit root, say that $L=1$ ...
• 2,807
1 vote
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### Time series: predicting covariates for missing years from historical values

I'm working with a time-series dataset where my dependent variable is measured annually from 2018-2021 but my covariates are not all measured over the same period. For instance, $x_1$ is measured from ...
• 131
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### What type of data we use to predict volatility of an asset with GARCH or ARCH models?

When we are trying to feed time-series data to a GARCH or ARCH model, what kind of data should we give the model? A: Absolute difference between daily prices over-time B: % of the difference between ...
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### Which econometric model should I use?

I have the following model Expenditures = a + $b_1$ Output + $b_2$ Labor + $b_3$ CapitalStock + $b_4$ D where D is dummy variable that is Categorical. If tax is imposed, it takes 1. Or if tax is not ...
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### AR(q) Strongly Stationary

Consider an AR(q) process, $u_t$. If the roots of a characteristic polynomial are outside of the unit circle, the AR(q) process is weakly stationary. I've seen this proof that proceeds by showing the ...
• 2,807
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### Estimation of variables

I am trying to estimate some variables, but I would like to know if what I am doing is right. I am using some data about labour productivity (in log) and, by using Stata, I filtered (Hodrick-Prescott) ...
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1 vote
115 views

### Finding consistent but inefficient GMM estimate

Consider the following linear model $$y_t = x_t' \beta +u_t$$ where $t =1,...,T$ and $x_t = (x_{1t} x_{2t} ... x_{kt})'$ , $\beta$ is $k \times 1$ vector of unknown coefficients, $u_t$ is an iid ...
• 334
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### Intercept in 2nd-stage Error Correction Model (ECM) regression — yes or no?

When doing a two-step ECM regression, do we add an intercept in the 2nd stage regression? I've seen course notes that add an intercept in the ECM, but some do not, so I'm confused if I should include ...
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1 vote
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### K-step ahead forecast of VAR(2)

I am trying to determine how to write the K-step ahead forecast of a VAR(2), with two variables, as a weighted average of its mean and last observations. I understand that one must use companion form, ...
• 261
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### IRF vs Autocorrelation function of AR(2)

Will the impulse response function and autocorrelation function of an AR(2) coincide? I say that they will not, because $IRF_{t}(t+k)$ (that is, the effect of a unit shock at time $t$, on the process ...
• 261
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### How to obtain real money balances data

Theoretically real money balances ($m_t$) are defined as: $m_t=\frac{M_t}{P_t}$ Where $M_t$ are nominal money balances, and $P_t$ is the price index of the economy. If I were to make an empirical ...
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1 vote
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### Detrending multiplicative model

I have a GDP quarterly series and IND.P monthly series, which I need to detrend. I am following Bernanke et al. paper from 1995 and the way they do it is: ...
27 views

### What does "sample period" in this case mean?

Dasgupta,2019 documented that the treated group comprises all firms that are headquartered in countries that have passed a leniency law by year t. The control group comprises firms in countries that ...
• 1,000
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### How to handle the missing values' issue of newly listed stocks?

I am trying to test some asset pricing models on 10 portfolios for the period of 2010-2020. The problem is that three of these portfolios included stocks that are newly listed in 2017 and 2018, so I ...
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1 vote
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### Examples of the use of Vector Autoregressive Models

I am self-learning Vector Autoregressive Models currently, and have practiced on a few datasets. But I wanted to read some actual research papers that use VAR, so that I get an idea of the level of ...
1 vote
40 views

### What is the importance of moving seasonality in seasonal adjustment?

Both Stable and Moving Seasonality are computed in Sliding span test (or D8 F-Stat test) and M7 statistics. But what is the purpose of finding out the presence of moving seasonality in seasonal ...
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