If you collected monthly data on housing construction and wanted to estimate new housing starts, you would want to include dummy variables

Select one:

a.both for warm-weather as well as for cold-weather months, to guarantee that all weather-related factors are accounted for.

b.for the Christmas season as well as for July.

c.for warm-weather months, as well as for the recent recession, since the housing market was strongly affected.

d.both for recessions and expansions to capture all phases of the business cycle.