The Stata Bookstore search engine lets you fine-tune your query to get the precise results that you’re looking for. Using the operators below, you can specify such details as what words to include/exclude, how to group search terms, and how different terms in your search phrase are ranked in the results.
| Symbol | Description | Example | Result |
|---|---|---|---|
| + | Indicates that a word must be present | +survival analysis | Returns results where "survival" must be present and "analysis" is optional |
| - | Indicates that a word must not be present | peanut -butter | Returns results where "peanut" is present but "butter" must not be present |
| > and < | Change a word's contribution to the relevance value that is assigned; > increases the contribution, whereas < decreases it | regression >survival <logistic | Returns results where "regression", "survival", or "logistic" are present; results with "survival" get ranked higher than results with "logistic" |
| ( ) | Group words into subexpressions; can be nested | +regression +(>diagnostics <analysis) | Returns results that contain "regression" and "diagnostics", or "regression and "analysis", in any order; "regression diagnostics" is ranked higher than "regression analysis" |
| ˜ | Causes a word's contribution to the result's relevance to be negative; a result containing such a word is ranked lower than others but is not excluded | +regression ˜logistic | Returns results that contain "regression"; if the result also contain "logistic", that result is included but with a lower ranking |
| * | Serves as the wildcard operator; words match if they begin with the character(s) preceding the * operator | statistic* | Returns results with "statistic", "statistics", or "statistical", etc. |
| " " | Searches only for entries containing the exact phrase | "statistical principles" | Returns results only where the exact phrase "statistical principles" is present; not case sensitive |