Primary analyses were conducted using Review Manager (RevMan), version 5.3 (Nordic Cochrane
https://community.cochrane.org/help/tools-and-software/revman-5
It can perform meta-analysis of the data entered, and present the results graphically. You can also useRevMan to write reviews of diagnostic test accuracy studies, reviews of studies of methodology and overviews of reviews. The latest major version, RevMan 5.3, was released on 13 June 2014.Centre, Cochrane Collaboration, Copenhagen, Denmark).
Subgroup and publication bias analyses were conducted using STATA software, version 13.0 (StataCorp, College Station, TX, USA).
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graphical path diagram builder • standardized and unstandardized estimates • modification indices • direct and indirect effects • continuous, binary, count, ordinal, and survival outcomes • multilevel models • random slopes and intercepts • factor scores, empirical Bayes, and other predictions • groups and tests of invariance • goodness of fit • handles MAR data by FIML • correlated data • survey data • more
Latent class analysis
binary, ordinal, continuous, count, categorical, fractional, and survival items • add covariates to model class membership • combine with SEM path models • expected class proportions • goodness of fit • predictions of class membership • more
Multiple imputation
nine univariate imputation methods • multivariate normal imputation • chained equations • explore pattern of missingness • manage imputed datasets • fit model and pool results • transform parameters • joint tests of parameter estimates • predictions • more
Survey methods
multistage designs • bootstrap, BRR, jackknife, linearized, and SDR variance estimation • poststratification • DEFF • predictive margins • means, proportions, ratios, totals • summary tables • almost all estimators supported • more
Cluster analysis
hierarchical clustering • kmeans and kmedian nonhierarchical clustering • dendrograms • stopping rules • user-extensible analyses • more
IRT (item response theory)
binary (1PL, 2PL, 3PL), ordinal, and categorical response models • item characteristic curves • test characteristic curves • item information functions • test information functions • differential item functioning (DIF) • more
Multivariate methods
factor analysis • principal components • discriminant analysis • rotation • multidimensional scaling • Procrustean analysis • correspondence analysis • biplots • dendrograms • user-extensible analyses • more
Data management
data transformations • match-merge • import/export data • ODBC • SQL • Unicode • by-group processing • append files • sort • row–column transposition • labeling • save results • more
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Graphical user interface
menus and dialogs for all features • Data Editor • Variables Manager • Graph Editor • Project Manager • Do-file Editor • Clipboard Preview Tool • multiple preference sets • more
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Basic statistics
summaries • cross-tabulations • correlations • z and t tests • equality-of-variance tests • tests of proportions • confidence intervals • factor variables • more
Nonparametric methods
nonparametric regression • Wilcoxon–Mann–Whitney, Wilcoxon signed ranks, and Kruskal–Wallis tests • Spearman and Kendall correlations • Kolmogorov–Smirnov tests • exact binomial CIs • survival data • ROC analysis • smoothing • bootstrapping • more
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standardization of rates • case–control • cohort • matched case–control • Mantel–Haenszel • pharmacokinetics • ROC analysis • ICD-10 • more
GMM and nonlinear regression
generalized method of moments (GMM) • nonlinear regression • more
Other statistical methods
kappa measure of interrater agreement • Cronbach's alpha • stepwise regression • tests of normality • more
Functions
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Mata—Stata's serious programming language
interactive sessions • large-scale development projects • optimization • matrix inversions • decompositions • eigenvalues and eigenvectors • LAPACK engine • real and complex numbers • string matrices • interface to Stata datasets and matrices • numerical derivatives • object-oriented programming • more
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Community-contributed commands
community-contributed commands for meta-analysis, data management, survival, econometrics, more
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Numerics by Stata
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Sample session
A sample session of Stata for Mac, Unix, or Windows.
New in Stata 15—Latent class analysis • Bayes prefix • Combine endogenous regressors, treatment effects, and selection • Spatial autoregressive models • Finite mixture models (FMM) • Markdown—create web pages with intermixed text, Stata output, and graphs • DSGE models • Nonlinear multilevel and panel-data models • Mixed logit choice models • Multilevel Bayesian analysis • Nonparametric regression • Interval-censored survival models • and much more
/* <![CDATA[ */ var google_conversion_id = 1021624005; var google_conversion_language = "en"; var google_conversion_format = "1"; var google_conversion_color = "ffffff"; var google_conversion_label = "mb-7CNfD-AEQxf2S5wM"; var google_conversion_value = 0; /* ]]> */
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We used qualitative analysis software (ATLAS.ti 5.0, Scientific Software Development, Berlin, Germany) to facilitate data organization and retrieval.
The Golden Rules of Google Searching
Before we discuss Google searching, we should understand some of the basic ground rules:
Google queries are not case sensitive. Google doesn’t care if you type your query in lowercase letters (hackers), uppercase (HACKERS), camel case (hAcKeR), or psycho-case (haCKeR)—the word is always regarded the same way. This is especially important when you’re searching things like source code listings, when the case of the term carries a great deal of meaning for the programmer. The one notable exception is the word or. When used as the Boolean operator, or must be written in uppercase, as OR.- Google -wildcards. Google’s concept of wildcards is not the same as a programmer’s concept of wildcards. Most consider wildcardsto be either a symbolic representation of any single letter (UNIX fans may think of the question mark) or any series of letters represented by an asterisk. This type of technique is called stemming. Google’s wildcard, the asterisk (*), represents nothing more than a single word in a search phrase. Using an asterisk at the beginning or end of a word will not provide you any more hits than using the word by itself.
- Google reserves the right to ignore you. Google ignores certain common words, characters, and single digits in a search. These are sometimes called stop words. According to Google’s basic search document (www.google.com/help/basics.html), these words include where and how, as shown in Figure 1.12. However, Google does seem to include those words in a search. For example, a search for WHERE 1 = 1 returns less results than a search for 1 = 1. This is an indication that the WHERE is being included in the search. A search for where pig returns significantly less results than a simple search for pig, again an indication that Google does in fact include words like how and where. Sometimes Google will silently ignore these stop words. For example, a search for HOW 1 = WHERE 4 returns the same number of results as a query for 1 = WHERE 4. This seems to indicate that the word HOW is irrelevant to the search results, and that Google silently ignored the word. There are no obvious rules for word exclusion, but sometimes when Google ignores a search term, a notification will appear on the results page just below the query box.
One way to force Google into using common words is to include them in quotes. Doing so submits the search as a phrase, and results will include all the words in the term, regardless of how common they may be. You can also precede the term with a + sign, as in the query +and. Submitted without the quotes, taking care not to put a space between the + and the word and, this search returns nearly five billion results!
Underground Googling…
Super-Size That Search!
One very interesting search is the search for of*. This search produces somewhere in the neighborhood of eighteen billion search results, making it one of the most prolific searches known! Can you top this search?
image 32–word limit Google limits searches to 32 words, which is up from the previous limit often words. This includes search terms as well as advanced operators, which we’ll discuss in a moment. While this is sufficient for most users, there are ways to get beyond that limit. One way is to replace some terms with the wildcard character (*). Google does not count the wildcard character as a search term, allowing you to extend your searches quite a bit. Consider a query for the wording of the beginning of the U.S. Constitution:
we the people of the united states in order to form a more perfect union establish justice
Underground Googling…
Bad Form on Purpose
In some cases, there’s nothing wrong with using poor Google syntax in a search. If Google safely ignores part of a human-friendly query, leave it alone. The human readers will thank you!
Quick Hex Conversions
To quickly determine hex codes for a character, you can run an American Standard Code for Information Interchange (ASCII) from a UNIX or Linux machine, or Google for the term “ascii table.”
Sticky Subject
The
hl value is sticky! This means that if you change this value in your URL, it sticks for future searches. The best way to change it back is through Google preferences or by changing the
hl code directly inside the URL.
intitle, allintitle
image inurl, allinurl
image filetype
image allintext
image site
image link
image inanchor
image daterange
image cache
image info
image related
image phonebook
image rphonebook
image bphonebook
image author
image group
image msgid
image insubject
image stocks
image define
Advanced operators are additions to a query designed to narrow down the search results. Although they re relatively easy to use, they have a fairly rigid syntax that must be followed. The basic syntax of an advanced operator is operator:search_term. When using advanced operators, keep in mind the following:
image There is no space between the operator, the colon, and the search term. Violating this syntax can produce undesired results and will keep Google from understanding what it is you’re trying to do. In most cases, Google will treat a syntactically bad advanced operator as just another search term. For example, providing the advanced operator intitle without a following colon and search term will cause Google to return pages that contain the word intitle.
image The search term portion of an operator search follows the syntax discussed in the previous chapter. For example, a search term can be a single word or a phrase surrounded by quotes. If you use a phrase, just make sure there are no spaces between the operator, the colon, and the first quote of the phrase.
image Boolean operators and special characters (such as OR and +) can still be applied to advanced operator queries, but be sure they don’t get in the way of the separating colon.
image Advanced operators can be combined in a single query as long as you honor both the basic Google query syntax as well as the advanced operator syntax. Some advanced operators combine better than others, and some simply cannot be combined. We will take a look at these limitations later in this chapter.
image The ALL operators (the operators beginning with the word ALL) are oddballs. They are generally used once per query and cannot be mixed with other operators.
Examples of valid queries that use advanced operators include these:
image intitle: Google This query will return pages that have the word Google in their title.
image intitle: “index of” This query will return pages that have the phrase index of in their title. Remember from the previous chapter that this query could also be given as intitle:index.of, since the period serves as any character. This technique also makes it easy to supply a phrase without having to type the spaces and the quotation marks around the phrase.
image intitle: “index of” private This query will return pages that have the phrase index of in their title and also have the word private anywhere in the page, including in the URL, the title, the text, and so on. Notice that intitle only applies to the phrase index of and not the word private, since the first unquoted space follows the phrase index of. Google interprets that space as the end of your advanced operator search term and continues processing the rest of the query.
image intitle: “index of” “backup files” This query will return pages that have the phrase index of in their title and the phrase backup files anywhere in the page, including the URL, the title, the text, and so on. Again, notice that intitle only applies to the phrase index of.
