General
PromptBeginner5 minmarkdownQuality: 24
- For Type III SS
use car::Anova() or set contrasts to contr.sum/contr.helmert.
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Showing 24 of 142,254Categories: General, Creative, Writing & Content, Coding & Debugging, Data
General
PromptBeginner5 minmarkdownQuality: 24
- Quasi-families (quasibinomial
quasipoisson) allow overdispersion — no AIC is computed.
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General
PromptBeginner5 minmarkdownQuality: 24
- binomial accepts response as: 0/1 vector
logical
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General
PromptBeginner5 minmarkdownQuality: 28
- `anova(glm_obj
test = Chisq) for deviance-based tests; F` is invalid for non-Gaussian families.
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General
PromptBeginner5 minmarkdownQuality: 28
- weights in glm means prior weights (not frequency weights) — for frequency weights
use the cbind trick or offset.
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General
PromptBeginner5 minmarkdownQuality: 24
- Column names from model.matrix can be surprising: e.g.
factorLevelName concatenation.
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General
PromptBeginner5 minmarkdownQuality: 24
- Common families: binomial(link = logit)
poisson(link = log)
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General
PromptBeginner5 minmarkdownQuality: 28
- Default family = gaussian(link = identity) — glm() with no family silently fits OLS (same as lm
but slower and with deviance-based output).
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General
PromptBeginner5 minmarkdownQuality: 28
- I() is required to use arithmetic operators literally: y ~ x + I(x^2). Without I()
^ means interaction crossing.
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General
PromptBeginner5 minmarkdownQuality: 24
- terms object attributes: order (interaction order per term)
intercept
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Creative
PromptBeginner5 minmarkdownQuality: 28
- model.matrix creates the design matrix including dummy coding. Default contrasts: contr.treatment...
contr.poly for ordered.
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General
PromptBeginner5 minmarkdownQuality: 24
- Captures output from cat
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General
PromptBeginner5 minmarkdownQuality: 24
Non-obvious behaviors
gotchas
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Coding & Debugging
PromptBeginner5 minmarkdownQuality: 24
- `URLencode(url
reserved = FALSE) by default does NOT encode reserved chars (/`
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General
PromptBeginner5 minmarkdownQuality: 24
- Converts character vectors to appropriate types (logical
integer
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General
PromptBeginner5 minmarkdownQuality: 24
- as.is = TRUE (recommended): keeps characters as character
not factor.
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General
PromptBeginner5 minmarkdownQuality: 24
- `formatC(x
format = f
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General
PromptBeginner5 minmarkdownQuality: 24
- Assignment form: `substr(x
1
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General
PromptBeginner5 minmarkdownQuality: 24
- `format(x
digits
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General
PromptBeginner5 minmarkdownQuality: 24
- which = both (default)
left
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General
PromptBeginner5 minmarkdownQuality: 24
- `substring(x
first
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Creative
PromptBeginner5 minmarkdownQuality: 24
- `substr(x
start
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General
PromptBeginner5 minmarkdownQuality: 24
- Common mistake: unnamed arguments silently match fixed
perl
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General
PromptBeginner5 minmarkdownQuality: 24
- Three regex modes: POSIX extended (default)
perl = TRUE
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