does an unobserved time invariant affect autocorrelation can time invariant variables cause autocorrelation do time invariants cause autocorrelation does pooled ols regression have any autocorrelation do time-invariant variables cause autocorrelation does pooled ols cause autocorrelation analysis can time invariant variables cause autocorrelation can unobserved time invariant variables cause autocorrelation does random effects cause autocorrelation why is a regression pooled does re create serial correlation what variable would cause autocorrelation does re model have serial correlation what model has autocorrelation can time invariant variables cause autocorrelation can time independent variables cause autocorrelation can time invariant variables cause autocorrelation? do time-invariant variables cause autocorrelation can unobserved time invariant variables cause autocorrelation can time-invariant regressions cause autocorrelation