मान लें हम regression कर रहे हैं

d = data.frame(y = 1:4, x1 = 1:4)
d$x2 = d$x1 + 1

अर्थात x2 = x1 + 1

जब हम multiple linear regression मॉडल फिट करते हैं

m = lm(y ~ x1 + x2, data = d)
summary(m)

# Some output removed 
# Warning message:
# In summary.lm(m) : essentially perfect fit: summary may be unreliable