Nicholas Cox is a statistically minded geographer at Durham University. He contributes talks, postings, FAQ, and programs to the Stata user community. He has also coauthored 16 commands in official Stata. He was an author of several inserts in the Stata Technical Bulletin and is Editor-at-Large of the Stata Journal.

• Introducing Stata tips Stata tip 120: Certifying subroutines, M. L. Buis Stata tip 121: Box plots side by side, N. J. Cox Stata tip 122: Variable bar widths in two-way graphs, B. Jann Stata tip 123: Spell boundaries, N. J. Cox Stata tip 124: Passing temporary variables to subprograms, M. L. Buis Stata tip 125: Binned residual plots for assessing the fit of regression models for binary outcomes, J. Kasza Stata tip 126: Handling irregularly spaced high-frequency transactions data, C. F. Baum and S. Bibo Stata tip 127: Use capture noisily groups, R. B. Newson Stata tip 128: Marginal effects in log-transformed models: A trade application, L. J. Uberti Stata tip 129: Efficiently processing textual data with Stata’s new Unicode features, A. Koplenig Stata tip 130: 106610 and all that: Date variables that need to be fixed., N. J. Cox Stata tip 131: Custom legends for graphs that use translucency, T. P. Morris Stata tip 132: Tiny tricks and tips on ticks, N. J. Cox and V. Wiggins Stata tip 133: Box plots that show median and quartiles only, N. J. Cox Stata tip 134: Multiplicative and marginal interaction effects in nonlinear models, W. H. Dow, E. C. Norton, and J. T. Donahoe Stata tip 135: Leaps and bounds, M. L. Buis Stata tip 136: Between-group comparisons in a scatterplot with weighted markers, A. Musau Stata tip 137: Interpreting constraints on slopes of rank-deficient design matrices, D. Christodoulou Stata tip 138: Local macros have local scope, N. J. Cox Stata tip 139: The by() option of graph can work better than graph combine, N. J. Cox Stata tip 140: Shorter or fewer category labels with graph bar, N. J. Cox Stata tip 141: Adding marginal spike histograms to quantile and cumulative distribution plots, N. J. Cox Stata tip 142: joinby is the real merge m:m, D. Mazrekaj and J. Wursten Stata tip 143: Creating donut charts in Stata, A. Musau Stata tip 144: Adding variable text to graphs that use a by() option, N. J. Cox Stata tip 145: Numbering weeks within months, N. J. Cox Stata tip 146: Using margins after a Poisson regression model to estimate the number of events prevented by an intervention, M. Falcaro, R. B. Newson, and P. Sasieni Erratum: Stata tip 145: Numbering weeks within months, N. J. Cox Stata tip 147: Porting downloaded packages between machines, R. B. Newson Stata tip 148: Searching for words within strings, N. J. Cox Stata tip 149: Weighted estimation of fixed-effects and first-differences models, J. Gardner Stata tip 150: When is it appropriate to xtset a panel dataset with panelvar only? C. Lazzaro Stata tip 151: Puzzling out some logical operators, N. J. Cox Stata tip 152: if and if: When to use the if qualifier and when to use the if command, N. J. Cox and C. B. Schechter