Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [differences]

The process of taking the difference between two values to achieve desirable statistical properties. e.g. paired differences t-test, differences between time points in an AR(1) model, and difference-in-differences causal impact analysis.

143 questions
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What is the difference between univariate and multivariate time series?

I have the following time series data: index Time value_1 value_2 value_3 0 2016-04-01 06:00:10 1 5 2 1 2016-04-01 06:00:20 2 9 8 2 2016-04-01 06:00:30 3 5 …
B.B
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What is the difference between econometrics and statistics?

It's never been very clear to me what distinguishes econometrics from statistics. My preliminary understanding was that statistics is data-focused whereas econometrics always starts from theory. But is that it? How are the two disciplines different?
FightMilk
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What is the relation between ELBO and SGVB?

Evidence lower bound (ELBO) can be maximized, so that to find the most appropriate approximative distribution of the target distribution, which is equivalent to the minimization of the corresponding Kullback–Leibler divergence. The paper that…
user82135
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Standard Error of the cumulative value for time series

I have two time series, as in the picture below. The data was gathered experimentally. A practical example could be a measured mass flow rate, where I measure the mass flow rate over a certain time period with changing boundary conditions, and I am…
John Tokka Tacos
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What "more" does differencing (d>0) do in ARIMA than detrend?

I recently read a discussion about ARIMA models where someone said (referring to d as in ARIMA (p, d, q)): Its true that d=1 takes out deterministic trends when they are present (they would appear only in the drift term.) But it does more than …
Wayne
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Why this OLS fitting will converge to (0,-0.5)?

In this AR1 model, if we fit y with diff(y), regardless the true coefficient, when N is large, it seems the model will converge to (0,-0.5), why? > set.seed(0) > ts.sim <- arima.sim(list(order = c(1,0,0), ar = c(0.1)), n = 1e6) > x= diff(ts.sim) >…
Haitao Du
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Levenshtein Distance vs Damerau Levenstein vs Optimal String Alignment Distance

Could anyone explain in simple words (and maybe with an example) what the difference between the Levenshtein Distance, Damerau Levenstein, and Optimal String Alignment Distance? When would one use one over the other distance algorithm? And the Math…
Pluviophile
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Is a time trend a substitute for first differencing?

I am doing a macroeconomic analysis involving BOP, investment ratio, GDP growth rates, and CPI inflation as dependent variables. My independent variables are other macro variables. When I test for unit root, many of the variables display unit root.…
econ_1889
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How many times should I difference a dataset?

Im currently reading The Foundation of Modern Time Series Analysis by Terrence C. Mills. In the fourth chapter he discusses the concept of difference data to remove secular trend and the history behind it. On page 36, section 4.7 it says: Cave and…
EconJohn
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Differences linear discriminant analysis and Gaussian mixture model

I know that there are topics about this question but in my view, the answers are not clear enough. I don't understand the main difference between Linear Discriminant Analysis (LDA) and Gaussian Mixture Models (GMM). Both have the same purpose :…
Mohamed
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Percentage change of interval data

My understanding is that the percentage/relative change is applicable/meaningful only with ratio data, and not with interval data. Can you confirm it is right, or correct me if it's wrong?
avignon96
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Formula for sample size for hypothesis test for difference in proportions confusion

For a hypothesis test for difference in proportions: Source A (some Stanford professor): The sample size for both groups is $$\frac{2\bar{p}(1-\bar{p})(Z_\beta+Z_{\alpha/2})^2}{(p_1-p_2)^2}$$ $$\bar{p}=\frac{p_1+p_2}{2}=p$$ Source B: Peter Dalgaard…
user294054
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Are Box-Cox and differencing redundant or complementary?

I was always under the impression that differencing and Box-Cox were two ways to achieve the same goal: Making a time series stationary so that it can be modeled using an ARMA process. However, looking at the code for auto.arima(), I notice that…
Akaike's Children
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What is the difference between belief propagation and loopy belief propagation?

Belief propagation (BP) is an algorithm (or a family of algorithms) that can be used to perform inference on graphical models (e.g. a Bayesian network). BP can produce exact results on cycle-free graphs (or trees). BP is a message passing algorithm:…
user82135
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Removing Unit Roots

If I have the following AR(p) process \begin{align} y_t=a_1 y_{t-1} + a_2 y_{t-2} + ... + a_p y_{t-p}+u_t, \end{align}where $ u_t $ is white noise, and I suppose the AR polynomial has 2 unit roots, how can I mathematically show that the process can…
KroneN
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