A 58-year-old man with type 2 diabetes (HbA1c 9.2%, fasting glucose 187 mg/dL) presents for cost analysis study enrollment. Linear regression models his HbA1c versus annual healthcare expenditure. Residual plots reveal heteroscedasticity: residual spread is minimal at predicted costs below $5,000 but progressively widens at costs exceeding $15,000. Blood pressure is 138/86 mmHg; no acute complications noted. Which regression assumption violation does this finding most strongly suggest?
- A)Multicollinearity
- B)HeteroscedasticityGABARITO
- C)Selection bias
- D)Interaction
- E)Confounding by indication
Explicação
Heteroscedasticity means the variance of residuals is not constant across the range of fitted values. The residual fan pattern described in the vignette is classic for this problem. It can lead to incorrect standard errors and misleading significance tests if ... Ver explicação completa e trilha adaptativa →