Econometrics

Aggregate Data
Data formed by combining many observations into totals, averages, or rates (for example GDP, inflation, unemployment).
ARFIMA
An autoregressive fractionally integrated moving average model that captures long memory via fractional differencing.
Autocorrelation Function (ACF)
A sequence of correlations between a time series and its own lagged values, used to describe persistence and guide time-series modeling.
Autoregressive Integrated Moving Average (ARIMA) Model
A time-series forecasting model that combines autoregression, differencing, and moving-average shocks.
Bandwidth (Nonparametric Estimation)
The smoothing window that controls how much neighboring data influence a nonparametric estimate.
Continuous Distribution
A probability distribution defined over a continuum of values, described by a density function.
Covariance Matrix
A square matrix that collects variances and covariances across multiple variables (used in econometrics and portfolio risk).
Detrending
The process of separating long-run trend movements from short-run fluctuations in economic time series.
Dickey-Fuller
A unit-root test used to assess whether a time series is nonstationary (has a unit root) or mean-reverting.
Discrete Distribution
A probability distribution for variables that take countable values, represented by a probability mass function.
Generalized Method of Moments (GMM) Estimator
An econometric estimator that fits parameters by matching model-implied moments to sample moments.
Goldfeld–Quandt Test
A heteroscedasticity test that compares residual variances across two subsamples ordered by a variable.
Interpolation
Estimating unknown values between observed data points (for example filling missing values within a time series).
Logistic Distribution
A continuous probability distribution with an S-shaped cumulative function, widely used in econometrics.
Omitted Variable Bias
Why regression estimates become biased when a relevant explanatory variable is left out.