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  2. Hat notation - Wikipedia

    en.wikipedia.org/wiki/Hat_notation

    In statistics, a circumflex (ˆ), called a "hat", is used to denote an estimator or an estimated value. [1] For example, in the context of errors and residuals , the "hat" over the letter ε ^ {\displaystyle {\hat {\varepsilon }}} indicates an observable estimate (the residuals) of an unobservable quantity called ε {\displaystyle \varepsilon ...

  3. Notation in probability and statistics - Wikipedia

    en.wikipedia.org/wiki/Notation_in_probability...

    Random variables are usually written in upper case Roman letters, such as or and so on. Random variables, in this context, usually refer to something in words, such as "the height of a subject" for a continuous variable, or "the number of cars in the school car park" for a discrete variable, or "the colour of the next bicycle" for a categorical variable.

  4. Glossary of mathematical symbols - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_mathematical...

    If y is a variable that depends on x, then , read as "d y over d x" (commonly shortened to "d y d x"), is the derivative of y with respect to x. 2. If f is a function of a single variable x , then d f d x {\displaystyle \textstyle {\frac {\mathrm {d} f}{\mathrm {d} x}}} is the derivative of f , and d f d x ( a ) {\displaystyle \textstyle {\frac ...

  5. Template:List of statistics symbols - Wikipedia

    en.wikipedia.org/wiki/Template:List_of...

    Main page; Contents; Current events; Random article; About Wikipedia; Contact us; Help; Learn to edit; Community portal; Recent changes; Upload file

  6. X bar - Wikipedia

    en.wikipedia.org/wiki/X_bar

    X bar, x̄ (or X̄) or X-bar may refer to: X-bar theory, a component of linguistic theory; Arithmetic mean, a commonly used type of average; An X-bar, a rollover protection structure; Roman numeral 10,000 in vinculum form

  7. Linear trend estimation - Wikipedia

    en.wikipedia.org/wiki/Linear_trend_estimation

    All have the same trend, but more filtering leads to higher r 2 of fitted trend line. The least-squares fitting process produces a value, r-squared (r 2), which is 1 minus the ratio of the variance of the residuals to the variance of the dependent variable. It says what fraction of the variance of the data is explained by the fitted trend line.

  8. Identity line - Wikipedia

    en.wikipedia.org/wiki/Identity_line

    The Keynesian cross diagram includes an identity line to show states in which aggregate demand equals output. In a 2-dimensional Cartesian coordinate system, with x representing the abscissa and y the ordinate, the identity line [1] [2] or line of equality [3] is the y = x line. The line, sometimes called the 1:1 line, has a slope of 1. [4]

  9. Vinculum (symbol) - Wikipedia

    en.wikipedia.org/wiki/Vinculum_(symbol)

    A vinculum (from Latin vinculum 'fetter, chain, tie') is a horizontal line used in mathematical notation for various purposes. It may be placed as an overline or underline above or below a mathematical expression to group the expression's elements.