SurveyFit | R Documentation |
An R6 SurveyFit
object stores a fitted model
object and provides methods for generating predicted probabilities for all
poststratification cells, generating population and group estimates, and
visualizing results.
new()
Create a new SurveyFit
object. This method is called
internally by the fit
method of the SurveyMap
object and does
not need to be called directly by the user.
SurveyFit$new(fit, map, formula)
fit
A fitted model object.
map
A SurveyMap
object.
formula
A formula object for the model that was fit.
A SurveyFit
object.
fit()
Access the fitted model object.
SurveyFit$fit()
The fitted model object created by the modeling function called
by the fit
method of the SurveyMap
object. For example, if using
rstanarm::stan_glmer()
then a stanreg
object from rstanarm is
returned.
map()
Access the SurveyMap
object.
SurveyFit$map()
The SurveyMap
associated with the SurveyFit
object.
formula()
Access the model formula.
SurveyFit$formula()
The model formula used when fitting the model.
print()
Call the fitted model object's print method. The console output from this method depends on the model fitting function used.
SurveyFit$print(...)
...
Optional arguments to pass the print method.
The SurveyFit
object, invisibly.
population_predict()
Use fitted model to add predicted probabilities to post-stratification dataset.
SurveyFit$population_predict(..., fun = NULL)
...
Arguments other than the fitted model object and
poststratification data frame to pass to fun
.
fun
The function to use to generate the predicted probabilities.
This should only be specified if you used a model fitting function
not natively supported by mrpkit.
For models fit using rstanarm, brms, or lme4, fun
is handled automatically. If fun
is specified then:
the first argument should be the fitted model object
the second argument should be the poststratification data frame
it can take an arbitrary number of other arguments
the returned object should match the specifications in the 'Returns' section below in order to be compatible with subsequent methods
A matrix with rows corresponding to poststratification cells and columns corresponding to posterior samples (or approximate ones in the case of lme4 models).
aggregate()
Aggregate estimates to the population level or by level of a grouping variable.
SurveyFit$aggregate(poststrat_estimates, by = NULL)
poststrat_estimates
The object returned by the population_predict
method.
by
Optionally a string specifying a grouping variable. If specified the aggregation will happen by level of the named variable. If not specified population-level estimates will be computed.
A data frame. If by
is not specified then the data frame will
have number of rows equal to the number of posterior draws. If by
is
specified the data frame will have number of rows equal to the number
of posterior draws times the number of levels of the by
variable,
and there will be an extra column indicating which level of the by
variable each row corresponds to.
summary()
Creates a set of summary statistics of the mrp estimate, and corresponding weighted and raw data estimates
SurveyFit$summary(aggregated_estimates)
aggregated_estimates
The data frame returned by the aggregate
method.
A data frame that consists of a minimum three rows with the raw, MRP
and weighted estimates, plus an estimate of standard error. If the aggregated estimates
were specified with a by
argument (indicating sub population or small area estimates),
then produces a dataframe with number of rows equal to three times the number of small areas.
plot()
Visualize population or sub-population estimates.
When passed the data frame containing the posterior distribution of the
population MRP estimate a density plot is generated. If visualizing
sub-populations it generates a violin plot of the posterior
distribution of the aggregated MRP estimates for each level of the
grouping variable. The additional_stats
argument controls which
other information is overlaid on the plot.
SurveyFit$plot(aggregated_estimates, additional_stats = c("wtd", "raw"))
aggregated_estimates
The data frame returned by the aggregate
method.
additional_stats
A vector that specifies which of three additional
stats ("wtd"
, "raw"
, "mrp"
, "none"
) should be overlaid on the
plot. The default is to overlay intervals for the weighted and raw
estimates on top of the density plot representing the MRP estimates.
The weighted estimates are computed by passing the optional survey
weights and design specified in the SurveyData
to the survey
package. The raw estimate is a direct mean and binomial sd of the
binary responses. Uncertainty estimates for the additional_stats
are
included on violin plots but not on density plots. Intervals are 95%
CI.
A ggplot object that is either a violin plot if showing small area level (sub-population) estimates, or a density plot if showing population estimates.
clone()
The objects of this class are cloneable with this method.
SurveyFit$clone(deep = FALSE)
deep
Whether to make a deep clone.
# Some fake survey data for demonstration
head(shape_survey)
# Create SurveyData object for the sample
box_prefs <- SurveyData$new(
data = shape_survey,
questions = list(
age = "Please identify your age group",
gender = "Please select your gender",
vote_for = "Which party did you vote for in the 2018 election?",
y = "If today is the election day, would you vote for the Box Party?"
),
responses = list(
age = levels(shape_survey$age),
gender = levels(shape_survey$gender),
# Here we use a data frame for the responses because the levels
# in the data are abridged versions of the actual responses.
# This can be useful when surveys have brief/non descriptive responses.
vote_for = data.frame(
data = levels(shape_survey$vote_for),
asked = c("Box Party Faction A", "Box Party Faction B",
"Circle Party Coalition", "Circle Party")
),
y = c("no", "yes")
),
weights = "wt",
design = list(ids =~1)
)
box_prefs$print()
box_prefs$n_questions()
# Some fake population data for demonstration
head(approx_voters_popn)
# Create SurveyData object for the population
popn_obj <- SurveyData$new(
data = approx_voters_popn,
questions = list(
age_group = "Which age group are you?",
gender = "Gender?",
vote_pref = "Which party do you prefer to vote for?"
),
# order doesn't matter (gender before age here) because
# the list has the names of the variables
responses = list(
gender = levels(approx_voters_popn$gender),
age_group = levels(approx_voters_popn$age_group),
vote_pref = levels(approx_voters_popn$vote_pref)
),
weights = "wt"
)
popn_obj$print()
# Create the QuestionMap objects mapping each question between the
# survey and population dataset
q_age <- QuestionMap$new(
name = "age",
col_names = c("age","age_group"),
values_map = list(
"18-25" = "18-35", "26-35" = "18-35","36-45" = "36-55",
"46-55" = "36-55", "56-65" = "56-65", "66-75" = "66+", "76-90" = "66+"
)
)
print(q_age)
q_party_pref <- QuestionMap$new(
name = "party_pref",
col_names = c("vote_for","vote_pref"),
values_map = list("Box Party" = "BP", "BP" = "BP","Circle Party" = "CP", "CP" = "CP")
)
q_gender <- QuestionMap$new(
name = "gender",
col_names = c("gender", "gender"),
values_map = list("male" = "m","female" = "f", "nonbinary" = "nb")
)
# Create SurveyMap object adding all questions at once
ex_map <- SurveyMap$new(
sample = box_prefs,
population = popn_obj,
q_age,
q_party_pref,
q_gender
)
print(ex_map) # or ex_map$print()
# Or can add questions incrementally
ex_map <- SurveyMap$new(sample = box_prefs, population = popn_obj)
print(ex_map)
ex_map$add(q_age, q_party_pref)
print(ex_map)
ex_map$add(q_gender)
print(ex_map)
# Create the mapping between sample and population
ex_map$mapping()
# Create the poststratification data frame using all variables in the mapping
# (alternatively, can specify particular variables, e.g. tabulate("age"))
ex_map$tabulate()
# Take a peak at the poststrat data frame
head(ex_map$poststrat_data())
## Not run:
# Fit regression model using rstanarm (returns a SurveyFit object)
fit_1 <- ex_map$fit(
fun = rstanarm::stan_glmer,
formula = y ~ (1|age) + (1|gender),
family = "binomial",
seed = 1111,
chains = 1, # just to keep the example fast and small
refresh = 0 # suppress printed sampling iteration updates
)
# To use lme4 or brms instead of rstanarm you would use:
# Example lme4 usage
# fit_2 <- ex_map$fit(
# fun = lme4::glmer,
# formula = y ~ (1|age) + (1|gender),
# family = "binomial"
# )
# Example brms usage
# fit_3 <- ex_map$fit(
# fun = brms::brm,
# formula = y ~ (1|age) + (1|gender),
# family = "bernoulli",
# seed = 1111
# )
# Predicted probabilities
# returns matrix with rows for poststrat cells, cols for posterior draws
poststrat_estimates <- fit_1$population_predict()
# Compute and summarize estimates by age level and party preference
estimates_by_age <- fit_1$aggregate(poststrat_estimates, by = "age")
estimates_by_party <- fit_1$aggregate(poststrat_estimates, by = "party_pref")
fit_1$summary(estimates_by_age)
fit_1$summary(estimates_by_party)
# Plot estimates
fit_1$plot(estimates_by_party)
fit_1$plot(estimates_by_age)
fit_1$plot(estimates_by_age, additional_stats = "none")
fit_1$plot(estimates_by_age, additional_stats = "wtd")
fit_1$plot(estimates_by_age, additional_stats = "raw")
fit_1$plot(estimates_by_age, additional_stats = c("wtd","raw","mrp"))
# Compute and summarize the population estimate
estimates_popn <- fit_1$aggregate(poststrat_estimates)
fit_1$summary(estimates_popn)
# Plot population estimate
fit_1$plot(estimates_popn)
fit_1$plot(estimates_popn, additional_stats = "none")
fit_1$plot(estimates_popn, additional_stats = "wtd")
fit_1$plot(estimates_popn, additional_stats = "raw")
fit_1$plot(estimates_popn, additional_stats = c("wtd","raw","mrp"))
## End(Not run)
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