Plotting Quadratic Moderating Effects using Regression Coefficients in Stata

📦 ssc install qmodplot If you've ever run a moderated regression with a quadratic term and wondered how to visualise it properly, this is for you. ━━━━━━━━━━━━━━━━━━━━━ WHAT IT DOES ━━━━━━━━━━━━━━━━━━━━━ qmodplot handles three models: ▸ Model 1 — linear x with a moderator ▸ Model 2 — U-shaped (quadratic) x with a moderator ▸ Model 3 — fully moderated curvature, where the moderator changes not just the vertex of the parabola but the steepness of the curve itself For every call it produces two graphs: ✅ Conditional curves — y = f(x) at several moderator reference points ✅ Marginal effect curves — dy/dx across the x range, with a zero reference line ━━━━━━━━━━━━━━━━━━━━━ WHAT MAKES IT DIFFERENT ━━━━━━━━━━━━━━━━━━━━━ 📌 Any number of moderator reference points — not just the standard low/medium/high. Binary (0 1), ordinal (1 2 3 4 5), or continuous cut-points (2000 3000 4000). Or let the data pick quantiles automatically. 📌 Delta-method confidence bands — semi-transparent shading so you can see the curves and overlapping bands at the same time. 📌 Turning-point table — reports exactly where the vertex of each parabola falls and whether it lies within your data range. 📌 Observation scatter — plots each data point (or panel-unit mean) as a labelled dot over the model curves. 📌 Reads straight from e(b)/e(V) after regress — no manual coefficient copying. ━━━━━━━━━━━━━━━━━━━━━ QUICK START ━━━━━━━━━━━━━━━━━━━━━ sysuse auto, clear gen mpgsq = mpg^2 gen mpgwt = mpg * weight regress price mpg mpgsq weight mpgwt qmodplot, model(2) fromereturn \\ xvar(mpg) xsqvar(mpgsq) mvar(weight) xmvar(mpgwt) \\ xname(MPG) mname(Weight) yname(Price) \\ xrange(12 41) mdata(weight) nquantiles(3) \\ ci cutstats combine ━━━━━━━━━━━━━━━━━━━━━ 🔗 GitHub: github.com/nomanarshed/qmodplot 📖 Install: ssc install qmodplot Feedback, bug reports, and feature requests are very welcome — open an issue on GitHub or drop a comment below. #Stata #Econometrics #StatisticalSoftware #OpenSource #ResearchMethods #DataVisualization #AcademicResearch #QuantitativeResearch #SSC #Moderation #Interaction #QuadraticRegression