Data
====

1. kiddiq.data.R
  - N         : number of observations
  - kid_score : cognitive test scores of three- and four-year-old children
  - mom_hs    : did mother complete high school? 1: Yes, 0: No
  - mom_iq    : mother IQ score
  - mom_hs_new: new data for prediction
  - mom_iq_new: new data for prediction

2. kids_before1987.data.R
  - N   : number of observations
  - afqt: normalized mother IQ score (mean = 100, sd = 15)
  - hs  : did mother complete high school? 1: Yes, 0: No
  - ppvt: cognitive test scores of children born before 1987

3. kids_after1987.data.R
  - afqt_ev: normalized mother IQ score (mean = 100, sd = 15)
  - hs_ev  : did mother complete high school? 1: Yes, 0: No
  - ppvt_ev: cognitive test scores of children born in 1987 or later

Models
======

1. One predictor
  kidscore_momhs.stan: lm(kid_score ~ mom_hs)
  kidscore_momiq.stan: lm(kid_score ~ mom_iq)

2. Multiple predictors with no interaction
  kidiq_multi_preds.stan: lm(kid_score ~ mom_hs + mom_iq)

3. Multiple predictors with interaction
  kidiq_interaction.stan: lm(kid_score ~ mom_hs + mom_iq + mom_hs:mom_iq)

4. Prediction
  kidiq_prediction.stan: 
   - fitted   : lm(kid_score ~ mom_hs + mom_iq)
   - predicted: lm(kid_score_pred ~ mom_hs_new + mom_iq_new)

5. External validation
  kidiq_validation.stan: 
   - fitted   : lm(ppvt ~ hs + afqt)
   - validated: R code