R$.$ Bucklin, R$.$ Caves, and A$.$ Lo estimated the following double$-$log model to explain the yearly circulation of metropolitan newspapers $($standard errors in parentheses$)$:$19,=-8\mathrm{.}2-0\mathrm{.}56$P$,+0\mathrm{.}901$; $+0\mathrm{.}76$Q; $+0\mathrm{.}27$A$,+0\mathrm{.}08$S$,-0\mathrm{.}77$T;$(0\mathrm{.}58)(0\mathrm{.}14)(0\mathrm{.}21)(0\mathrm{.}14)(0\mathrm{.}05)(0\mathrm{.}27)$N $=50$where:C; $=$ yearly circulation of the ith newspaperPj $=$ the weighted average single copy price of the ithnewspaperI; $=$ the total disposable income of the metropolitan areaof the ith newspaperQi $=$ the number of personnel in editorial positions at theith newspaperAj $=$ the volume of retail advertising in the ith newspaperS; $=$ amount of competition from suburban dailies in theith newspaper's regionT; $=$ the number of television stations in the ith newspaper's region$($All variables are in logarithmic form.$)$a$.$ Hypothesize signs and run t$-$tests on each of the individual slope coefficients.b$.$ Does heteroskedasticity seem theoretically likely? Explain.c$.$ Given your responses to parts a and b$,$ what econometric problems $($out of omitted variables, irrelevant variables, incorrect functional form, multicollinearity, serial correlation, and heteroskedasticity$)$appear to exist in this equation?d$.$ If you could suggest just one change in the specification of this equa$-$tion, what would that change be$?$ Carefully explain your answer.