How is a nation's road system related to its weatleh and population density? To answer this question, the following variables were deemed reasonably relevant and accessible for each of $113$ countries in $1968($Glover and Simon, $1975)$: The logarithmic multiple regraession was computed to be

log R $=-6\mathrm{.}43+1\mathrm{.}17$ log P $+1\mathrm{.}10$ log I

$($SE$)(0\mathrm{.}053)(0\mathrm{.}07)$