แก้ไขปัญหาด้วยการวินิจฉัยโมเดล

library(mgcv)
# Fit the model
mod <- gam(y ~ s(x0, k = 3) + s(x1, k = 3) + s(x2, k = 3) + s(x3, k = 3),
           data = dat, method = "REML")

# Check the diagnostics
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# Refit to fix issues
mod2 <- gam(y ~ s(x0, k = ___) + s(x1, k = ___) + s(x2, k = ___) + s(x3, k = ___),
           data = dat, method = "REML")

# Check the new model
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