Prediction

In-class example

Here’s the code we’ll be using in class. Download it and store it with the rest of your materials for this course. If simply clicking doesn’t trigger download, you should right-click and select “save link as…”

Art

How much should we expect a painting to sell for if it was created in 2000, is a sculpture, is 360 inches, painted by a male artist who went to an elite art school?

Step 1: fit model

art_mod = lm(real_price_usd ~ year_of_artwork + genre + size_inch_by_inch + gender_male + elite_school, data = art)
tidy(art_mod)
# A tibble: 14 × 5
   term                 estimate std.error statistic  p.value
   <chr>                   <dbl>     <dbl>     <dbl>    <dbl>
 1 (Intercept)         -871468.  423020.    -2.06    3.94e- 2
 2 year_of_artwork         399.     180.     2.22    2.65e- 2
 3 genreFurniture       -22050.  233258.    -0.0945  9.25e- 1
 4 genreLighting         16834.  279905.     0.0601  9.52e- 1
 5 genrePaintings       131746.  221991.     0.593   5.53e- 1
 6 genrePhotographs      38462.  225012.     0.171   8.64e- 1
 7 genrePrints            8849.  223350.     0.0396  9.68e- 1
 8 genresculpture       502219.  585437.     0.858   3.91e- 1
 9 genreSculpture        95405.  221369.     0.431   6.66e- 1
10 genreTextiles          -502.  312996.    -0.00160 9.99e- 1
11 genreWorks on Paper   22696.  224533.     0.101   9.19e- 1
12 size_inch_by_inch        27.6      1.36  20.3     8.00e-90
13 gender_male           62918.   15183.     4.14    3.44e- 5
14 elite_school          76471.   11665.     6.56    5.76e-11

Step 2: set scenario:

art_scen = crossing(year_of_artwork = 2000, genre = "Sculpture", size_inch_by_inch = 360, gender_male = 1, elite_school = 1)
art_scen
# A tibble: 1 × 5
  year_of_artwork genre     size_inch_by_inch gender_male elite_school
            <dbl> <chr>                 <dbl>       <dbl>        <dbl>
1            2000 Sculpture               360           1            1

Step 3: get estimate:

augment(art_mod, newdata = art_scen)
# A tibble: 1 × 6
  year_of_artwork genre     size_inch_by_inch gender_male elite_school .fitted
            <dbl> <chr>                 <dbl>       <dbl>        <dbl>   <dbl>
1            2000 Sculpture               360           1            1 170745.