“dummy variable”的概念、定义、翻译、参考文献-科学参考

dummy variable

Mathematics

A variable appearing in an expression is a dummy variable if the letter being used could equally well be replaced by another letter. For example, the two expressions

$\int_{0}^{1} x^{2} d x and \int_{0}^{1} t^{2} d t$

represent the same definite integral, and so x and t are dummy variables. Similarly, the summation

$\sum_{r = 1}^{5} r^{2}$

denotes the sum 1² + 2² + 3² + 4² + 5² and would still do so if the letter r were replaced by the letter s, say; so r here is a dummy variable.

Statistics

A variable, taking only the values 0 and 1, derived from a polytomous categorical variable. If the categorical variable has k categories then (k−1) dummy variables are required. For example, with four categories the three dummy variables (x₁, x₂, x₃) could be assigned the values (1, 0, 0) for category 1, (0, 1, 0) for category 2, (0, 0, 1) for category 3, and (0, 0, 0) for category 4. Dummy variables enable the inclusion of categorical information in multiple regression models.

Electronics and Electrical Engineering

A variable in an equation or expression whose possible values have been restricted in some way. For example, in the equation a + b = c, we can consider all three variables to be unbound, or free, in that they can take on arbitrary numeric values. Some of these values will result in the equation being true, while others will make it false. However, if we qualify the equation, for example, asking for the b that satisfies a + b = c, then b becomes bound and is now a dummy variable, whose value depends on those of a and c, which are still free. Dummy variables can always be replaced systematically by another variable not already in use without altering the meaning of the equation. In an integral such as $\int f (x) d x$ , x is a dummy variable, so we do not change the meaning by rewriting it as $\int f (t) d t$ .

Economics

See categorical variable.

单词	dummy variable
释义	dummy variable Mathematics A variable appearing in an expression is a dummy variable if the letter being used could equally well be replaced by another letter. For example, the two expressions $\int_{0}^{1} x^{2} d x and \int_{0}^{1} t^{2} d t$ represent the same definite integral, and so x and t are dummy variables. Similarly, the summation $\sum_{r = 1}^{5} r^{2}$ denotes the sum 1² + 2² + 3² + 4² + 5² and would still do so if the letter r were replaced by the letter s, say; so r here is a dummy variable. Statistics A variable, taking only the values 0 and 1, derived from a polytomous categorical variable. If the categorical variable has k categories then (k−1) dummy variables are required. For example, with four categories the three dummy variables (x₁, x₂, x₃) could be assigned the values (1, 0, 0) for category 1, (0, 1, 0) for category 2, (0, 0, 1) for category 3, and (0, 0, 0) for category 4. Dummy variables enable the inclusion of categorical information in multiple regression models. Electronics and Electrical Engineering A variable in an equation or expression whose possible values have been restricted in some way. For example, in the equation a + b = c, we can consider all three variables to be unbound, or free, in that they can take on arbitrary numeric values. Some of these values will result in the equation being true, while others will make it false. However, if we qualify the equation, for example, asking for the b that satisfies a + b = c, then b becomes bound and is now a dummy variable, whose value depends on those of a and c, which are still free. Dummy variables can always be replaced systematically by another variable not already in use without altering the meaning of the equation. In an integral such as $\int f (x) d x$ , x is a dummy variable, so we do not change the meaning by rewriting it as $\int f (t) d t$ . Economics See categorical variable.
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