Tidy summarizes information about the components of a model. A model component might be a single term in a regression, a single hypothesis, a cluster, or a class. Exactly what tidy considers to be a model component varies across models but is usually self-evident. If a model has several distinct types of components, you will need to specify which components to return.
The particular functions below provide generic tidy methods for
objects returned by the mfx package, preserving the calculated marginal
effects instead of the naive model coefficients. The returned tidy tibble
will also include an additional "atmean" column indicating how the marginal
effects were originally calculated (see Details below).
Usage
# S3 method for mfx
tidy(x, conf.int = FALSE, conf.level = 0.95, ...)
# S3 method for logitmfx
tidy(x, conf.int = FALSE, conf.level = 0.95, ...)
# S3 method for negbinmfx
tidy(x, conf.int = FALSE, conf.level = 0.95, ...)
# S3 method for poissonmfx
tidy(x, conf.int = FALSE, conf.level = 0.95, ...)
# S3 method for probitmfx
tidy(x, conf.int = FALSE, conf.level = 0.95, ...)Arguments
- x
A
logitmfx,negbinmfx,poissonmfx, orprobitmfxobject. (Note thatbetamfxobjects receive their own set of tidiers.)- conf.int
Logical indicating whether or not to include a confidence interval in the tidied output. Defaults to
FALSE.- conf.level
The confidence level to use for the confidence interval if
conf.int = TRUE. Must be strictly greater than 0 and less than 1. Defaults to 0.95, which corresponds to a 95 percent confidence interval.- ...
Additional arguments. Not used. Needed to match generic signature only. Cautionary note: Misspelled arguments will be absorbed in
..., where they will be ignored. If the misspelled argument has a default value, the default value will be used. For example, if you passconf.lvel = 0.9, all computation will proceed usingconf.level = 0.95. Two exceptions here are:
Details
The mfx package provides methods for calculating marginal effects
for various generalized linear models (GLMs). Unlike standard linear
models, estimated model coefficients in a GLM cannot be directly
interpreted as marginal effects (i.e., the change in the response variable
predicted after a one unit change in one of the regressors). This is
because the estimated coefficients are multiplicative, dependent on both
the link function that was used for the estimation and any other variables
that were included in the model. When calculating marginal effects, users
must typically choose whether they want to use i) the average observation
in the data, or ii) the average of the sample marginal effects. See
vignette("mfxarticle") from the mfx package for more details.
See also
tidy(), mfx::logitmfx(), mfx::negbinmfx(), mfx::poissonmfx(), mfx::probitmfx()
Other mfx tidiers:
augment.betamfx(),
augment.mfx(),
glance.betamfx(),
glance.mfx(),
tidy.betamfx()
Value
A tibble::tibble() with columns:
- conf.high
Upper bound on the confidence interval for the estimate.
- conf.low
Lower bound on the confidence interval for the estimate.
- estimate
The estimated value of the regression term.
- p.value
The two-sided p-value associated with the observed statistic.
- statistic
The value of a T-statistic to use in a hypothesis that the regression term is non-zero.
- std.error
The standard error of the regression term.
- term
The name of the regression term.
- atmean
TRUE if the marginal effects were originally calculated as the partial effects for the average observation. If FALSE, then these were instead calculated as average partial effects.
Examples
# load libraries for models and data
library(mfx)
# get the marginal effects from a logit regression
mod_logmfx <- logitmfx(am ~ cyl + hp + wt, atmean = TRUE, data = mtcars)
tidy(mod_logmfx, conf.int = TRUE)
#> # A tibble: 3 × 8
#> term atmean estimate std.error statistic p.value conf.low conf.high
#> <chr> <lgl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 cyl TRUE 0.0538 0.113 0.475 0.635 -0.178 0.286
#> 2 hp TRUE 0.00359 0.00290 1.24 0.216 -0.00236 0.00954
#> 3 wt TRUE -1.01 0.668 -1.51 0.131 -2.38 0.359
# compare with the naive model coefficients of the same logit call
tidy(
glm(am ~ cyl + hp + wt, family = binomial, data = mtcars),
conf.int = TRUE
)
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> # A tibble: 4 × 7
#> term estimate std.error statistic p.value conf.low conf.high
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 (Intercept) 19.7 8.12 2.43 0.0152 8.56 44.3
#> 2 cyl 0.488 1.07 0.455 0.649 -1.53 3.12
#> 3 hp 0.0326 0.0189 1.73 0.0840 0.00332 0.0884
#> 4 wt -9.15 4.15 -2.20 0.0276 -21.4 -3.48
augment(mod_logmfx)
#> # A tibble: 32 × 11
#> .rownames am cyl hp wt .fitted .resid .hat .sigma .cooksd
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 Mazda RX4 1 6 110 2.62 2.24 0.449 0.278 0.595 1.42e-2
#> 2 Mazda RX… 1 6 110 2.88 -0.0912 1.22 0.352 0.529 2.30e-1
#> 3 Datsun 7… 1 4 93 2.32 3.46 0.249 0.0960 0.602 9.26e-4
#> 4 Hornet 4… 0 6 110 3.22 -3.20 -0.282 0.0945 0.601 1.17e-3
#> 5 Hornet S… 0 8 175 3.44 -2.17 -0.466 0.220 0.595 1.03e-2
#> 6 Valiant 0 6 105 3.46 -5.61 -0.0856 0.0221 0.604 2.12e-5
#> 7 Duster 3… 0 8 245 3.57 -1.07 -0.766 0.337 0.576 6.55e-2
#> 8 Merc 240D 0 4 62 3.19 -5.51 -0.0897 0.0376 0.603 4.10e-5
#> 9 Merc 230 0 4 95 3.15 -4.07 -0.184 0.122 0.603 6.76e-4
#> 10 Merc 280 0 6 123 3.44 -4.84 -0.126 0.0375 0.603 8.02e-5
#> # ℹ 22 more rows
#> # ℹ 1 more variable: .std.resid <dbl>
glance(mod_logmfx)
#> # A tibble: 1 × 8
#> null.deviance df.null logLik AIC BIC deviance df.residual nobs
#> <dbl> <int> <dbl> <dbl> <dbl> <dbl> <int> <int>
#> 1 43.2 31 -4.92 17.8 23.7 9.84 28 32
# another example, this time using probit regression
mod_probmfx <- probitmfx(am ~ cyl + hp + wt, atmean = TRUE, data = mtcars)
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
tidy(mod_probmfx, conf.int = TRUE)
#> # A tibble: 3 × 8
#> term atmean estimate std.error statistic p.value conf.low conf.high
#> <chr> <lgl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 cyl TRUE 0.0616 0.112 0.548 0.583 -0.169 0.292
#> 2 hp TRUE 0.00383 0.00282 1.36 0.174 -0.00194 0.00960
#> 3 wt TRUE -1.06 0.594 -1.78 0.0753 -2.27 0.160
augment(mod_probmfx)
#> # A tibble: 32 × 11
#> .rownames am cyl hp wt .fitted .resid .hat .sigma .cooksd
#> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 Mazda RX4 1 6 110 2.62 1.21 0.490 0.308 0.585 2.05e-2
#> 2 Mazda RX… 1 6 110 2.88 -0.129 1.27 0.249 0.526 1.36e-1
#> 3 Datsun 7… 1 4 93 2.32 1.85 0.256 0.134 0.594 1.48e-3
#> 4 Hornet 4… 0 6 110 3.22 -1.92 -0.237 0.116 0.594 1.05e-3
#> 5 Hornet S… 0 8 175 3.44 -1.25 -0.474 0.236 0.587 1.20e-2
#> 6 Valiant 0 6 105 3.46 -3.30 -0.0312 0.0111 0.596 1.39e-6
#> 7 Duster 3… 0 8 245 3.57 -0.595 -0.804 0.285 0.567 5.32e-2
#> 8 Merc 240D 0 4 62 3.19 -3.31 -0.0304 0.0179 0.596 2.15e-6
#> 9 Merc 230 0 4 95 3.15 -2.47 -0.116 0.130 0.596 2.89e-4
#> 10 Merc 280 0 6 123 3.44 -2.85 -0.0662 0.0315 0.596 1.84e-5
#> # ℹ 22 more rows
#> # ℹ 1 more variable: .std.resid <dbl>
glance(mod_probmfx)
#> # A tibble: 1 × 8
#> null.deviance df.null logLik AIC BIC deviance df.residual nobs
#> <dbl> <int> <dbl> <dbl> <dbl> <dbl> <int> <int>
#> 1 43.2 31 -4.80 17.6 23.5 9.59 28 32