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\details{
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\details{
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  \code{print.summary.lm} tries to be smart about formatting the
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  \code{print.summary.lm} tries to be smart about formatting the
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  coefficients, standard errors, etc. and additionally gives
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  coefficients, standard errors, etc. and additionally gives
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  \sQuote{significance stars} if \code{signif.stars} is \code{TRUE}.
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  \sQuote{significance stars} if \code{signif.stars} is \code{TRUE}.
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  Aliased coefficients are omitted in the returned object but restored
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  by the \code{print} method.
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  Correlations are printed to two decimal places (or symbolically): to
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  Correlations are printed to two decimal places (or symbolically): to
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  see the actual correlations print \code{summary(object)$correlation}
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  see the actual correlations print \code{summary(object)$correlation}
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  directly.
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  directly.
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}
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}
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\value{
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\value{
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    coefficients are aliased.}
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    coefficients are aliased.}
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  \item{sigma}{the square root of the estimated variance of the random
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  \item{sigma}{the square root of the estimated variance of the random
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    error
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    error
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    \deqn{\hat\sigma^2 = \frac{1}{n-p}\sum_i{w_i R_i^2},}{\sigma^2 = 1/(n-p) Sum(w[i] R[i]^2),}
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    \deqn{\hat\sigma^2 = \frac{1}{n-p}\sum_i{w_i R_i^2},}{\sigma^2 = 1/(n-p) Sum(w[i] R[i]^2),}
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    where \eqn{R_i}{R[i]} is the \eqn{i}-th residual, \code{residuals[i]}.}
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    where \eqn{R_i}{R[i]} is the \eqn{i}-th residual, \code{residuals[i]}.}
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  \item{df}{degrees of freedom, a 3-vector \eqn{(p, n-p, p*)}, the last
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  \item{df}{degrees of freedom, a 3-vector \eqn{(p, n-p, p*)}, the first
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    being the number of non-aliased coefficients.}
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    being the number of non-aliased coefficients, the last being the total
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    number of coefficients.}
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  \item{fstatistic}{(for models including non-intercept terms)
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  \item{fstatistic}{(for models including non-intercept terms)
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    a 3-vector with the value of the F-statistic with
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    a 3-vector with the value of the F-statistic with
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    its numerator and denominator degrees of freedom.}
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    its numerator and denominator degrees of freedom.}
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  \item{r.squared}{\eqn{R^2}, the \sQuote{fraction of variance explained by
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  \item{r.squared}{\eqn{R^2}, the \sQuote{fraction of variance explained by
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    the model},
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    the model},
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##-- Continuing the  lm(.) example:
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##-- Continuing the  lm(.) example:
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coef(lm.D90)  # the bare coefficients
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coef(lm.D90)  # the bare coefficients
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sld90 <- summary(lm.D90 <- lm(weight ~ group -1))  # omitting intercept
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sld90 <- summary(lm.D90 <- lm(weight ~ group -1))  # omitting intercept
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sld90
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sld90
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coef(sld90)  # much more
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coef(sld90)  # much more
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## model with *aliased* coefficient:
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lm.D9. <- lm(weight ~ group + I(group != "Ctl"))
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Sm.D9. <- summary(lm.D9.)
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Sm.D9. #  shows the NA NA NA NA  line
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stopifnot(length(cc <- coef(lm.D9.)) == 3, is.na(cc[3]),
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          dim(coef(Sm.D9.)) == c(2,4), Sm.D9.$df == c(2, 18, 3))
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}
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}
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\keyword{regression}
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\keyword{regression}
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\keyword{models}
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\keyword{models}