FIX Hub — Technical Troubleshooting & Diagnostics

These FIX pages target assumption violations and inference breakdowns that derail statistical models — essential for graduate statistics tutoring.

• Fix ANOVA assumption violations in SPSS — SPSS ANOVA breaks when normality, variance, or independence assumptions fail.
• Fix OLS multicollinearity in R — High VIFs and unstable coefficients signal redundant predictors.
• Fix heteroskedasticity & robust SEs in R — Robust SEs fail when variance estimators or model objects are mis‑specified.
• Fix robust standard errors in Stata — Incorrect clustering or syntax leads to invalid inference.
• Fix hazard vs survival function — Students confuse instantaneous risk with cumulative probability.
• Fix Cox proportional hazards — PH violations cause Cox models to fail.

These FIX pages address regression diagnostics, GLM convergence, and interpretation errors — core issues in regression tutoring.

• Fix regression diagnostics in SPSS — SPSS diagnostics break when assumptions or plots are misinterpreted.
• Fix logistic regression output in SAS — SAS output breaks when class statements or formats misalign.
• Fix logit/probit convergence in R — Convergence fails due to separation or scaling issues.
• Fix logit/probit interpretation in Stata — Students confuse coefficients, odds ratios, and marginal effects.

These FIX pages resolve econometric inference failures — essential for econometrics tutoring and causal modeling support.

• Fix endogeneity in OLS — Omitted variables or simultaneity bias coefficients.
• Fix clustered standard errors — Clustering corrects correlated shocks that break classical inference.
• Fix fixed vs random effects in Stata — FE/RE selection fails when variation is insufficient.

These FIX pages address time‑series structure failures — essential for forecasting tutoring and econometrics tutoring.

• Fix non‑stationary time series in R — Differencing, detrending, or transformations are often misapplied.
• Fix time‑series lag selection in Stata — Lag criteria fail when differencing or model structure is incorrect.
• Fix time series errors in EViews — EViews breaks when frequency, structure, or transformations are inconsistent.
• Fix time series fails stationarity tests — Drift or structural breaks violate assumptions.

These FIX pages resolve software‑specific execution failures in statistical packages — essential for coding‑based statistics tutoring.

• Fix factor reference levels in R — Incorrect baselines distort regression interpretation.
• Fix Python statsmodels output doesn’t match class notes — Defaults differ across packages and versions.

These FIX pages address reproducibility failures, inconsistent outputs, and dataset corruption — core issues in graduate research tutoring.

• Fix dataset changes after export/import — Encoding, delimiter, or factor‑level corruption alters structure.
• Fix R code works on one dataset but not another — Structural differences or missing values break pipelines.
• Fix regression output keeps changing — Hidden filters or overwritten data cause shifting results.

These FIX pages resolve optimization, simulation, and financial modeling failures — essential for management science tutoring and finance tutoring.

• Fix Solver infeasible errors in Excel — Contradictory constraints eliminate feasible solutions.
• Fix Crystal Ball simulation optimization — Simulation fails when assumptions or constraints conflict.
• Fix Palisade @RISK optimization — @RISK breaks when simulation settings misalign.
• Fix binomial tree pricing in Excel — Errors arise from incorrect up/down factors or payoff formulas.
• Fix option payoff graphs in Excel — Payoff charts break when strike logic is mis‑specified.
• Fix newsvendor model errors in Excel — Demand distributions or cost parameters are mis‑entered.
• Fix NPV vs IRR disagreement in Excel — Conflicts arise from non‑conventional cash flows.
• Fix time value of money cash flows in Excel — TVM errors stem from wrong signs or timing conventions.

These FIX pages address accounting imbalances and financial statement logic — essential for finance tutoring and accounting support.

• Fix balance sheet not balancing — Retained earnings or misclassified entries cause imbalances.
• Fix debits & credits not balancing — Journal entries are incomplete or misposted.
• Fix statement of cash flows not working — Operating, investing, and financing sections misalign.