Lahman

library(tidyverse)
library(Lahman)

Teams %>%
  filter(yearID == 2000) %>%
  select(teamID, franchID,
         divID, lgID, W, L, R, G, RA) %>% 
  rename(wins = W, losses = L,
         runs = R, games = G,
         runs_opponent = RA) %>%
  mutate(win_pct = wins/games) %>%
  mutate(runs_differential = runs - runs_opponent) ->
my_data

my_data %>% 
  head()

##   teamID franchID divID lgID wins losses runs games runs_opponent   win_pct
## 1    ANA      ANA     W   AL   82     80  864   162           869 0.5061728
## 2    ARI      ARI     W   NL   85     77  792   162           754 0.5246914
## 3    ATL      ATL     E   NL   95     67  810   162           714 0.5864198
## 4    BAL      BAL     E   AL   74     88  794   162           913 0.4567901
## 5    BOS      BOS     E   AL   85     77  792   162           745 0.5246914
## 6    CHA      CHW     C   AL   95     67  978   162           839 0.5864198
##   runs_differential
## 1                -5
## 2                38
## 3                96
## 4              -119
## 5                47
## 6               139

my_data %>%
  ggplot() +
  aes(y = wins) +
  aes(x = runs_differential) +
  geom_rug() +
  geom_point() +
  geom_smooth(method = lm, se = F) +
  ggxmean::geom_lm_formula() +
  aes(color = lgID) +
  facet_wrap(facets = vars(lgID))

## `geom_smooth()` using formula 'y ~ x'

my_data %>%
  lm(formula = wins ~ 
       runs_differential + lgID +
       lgID*runs_differential, data = .) %>% 
  summary

## 
## Call:
## lm(formula = wins ~ runs_differential + lgID + lgID * runs_differential, 
##     data = .)
## 
## Residuals:
##    Min     1Q Median     3Q    Max 
## -7.988 -1.740 -0.246  2.116  6.368 
## 
## Coefficients:
##                          Estimate Std. Error t value Pr(>|t|)    
## (Intercept)              81.38362    0.90885   89.55  < 2e-16 ***
## runs_differential         0.08065    0.00906    8.91  2.2e-09 ***
## lgIDNL                   -0.78447    1.24443   -0.63    0.534    
## runs_differential:lgIDNL  0.02127    0.01242    1.71    0.099 .  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3.4 on 26 degrees of freedom
## Multiple R-squared:  0.896,  Adjusted R-squared:  0.884 
## F-statistic: 74.8 on 3 and 26 DF,  p-value: 6.51e-13