draw_discrete: Draw discrete variables including binary, binomial count,...

Description Usage Arguments Details Value Examples

Description

Drawing discrete data based on probabilities or latent traits is a common task that can be cumbersome. Each function in our discrete drawing set creates a different type of discrete data: draw_binary creates binary 0/1 data, draw_binomial creates binomial data (repeated trial binary data), draw_categorical creates categorical data, draw_ordered transforms latent data into observed ordered categories, draw_count creates count data (poisson-distributed). draw_likert is an alias to draw_ordered that pre-specifies break labels and offers default breaks appropriate for a likert survey question.

Usage

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draw_binomial(prob = link(latent), trials = 1, N = length(prob),
  latent = NULL, link = "identity", quantile_y = NULL)

draw_categorical(prob = link(latent), N = NULL, latent = NULL,
  link = "identity", category_labels = NULL)

draw_ordered(x = link(latent), breaks = c(-1, 0, 1),
  break_labels = NULL, N = length(x), latent = NULL,
  strict = FALSE, link = "identity")

draw_count(mean = link(latent), N = length(mean), latent = NULL,
  link = "identity", quantile_y = NULL)

draw_binary(prob = link(latent), N = length(prob), link = "identity",
  latent = NULL, quantile_y = NULL)

draw_likert(x, type = 7, breaks = NULL, N = length(x),
  latent = NULL, link = "identity", strict = !is.null(breaks))

draw_quantile(type, N)

Arguments

prob

A number or vector of numbers representing the probability for binary or binomial outcomes; or a number, vector, or matrix of numbers representing probabilities for categorical outcomes. If you supply a link function, these underlying probabilities will be transformed.

trials

for draw_binomial, the number of trials for each observation

N

number of units to draw. Defaults to the length of the vector of probabilities or latent data you provided.

latent

If the user provides a link argument other than identity, they should provide the variable latent rather than prob or mean

link

link function between the latent variable and the probability of a positive outcome, e.g. "logit", "probit", or "identity". For the "identity" link, the latent variable must be a probability.

quantile_y

A vector of quantiles; if provided, rather than drawing stochastically from the distribution of interest, data will be drawn at exactly those quantiles.

category_labels

vector of labels for the categories produced by draw_categorical. If provided, must be equal to the number of categories provided in the prob argument.

x

for draw_ordered or draw_likert, the latent data for each observation.

breaks

vector of breaks to cut a latent outcome into ordered categories with draw_ordered or draw_likert

break_labels

vector of labels for the breaks to cut a latent outcome into ordered categories with draw_ordered. (Optional)

strict

Logical indicating whether values outside the provided breaks should be coded as NA. Defaults to FALSE, in which case effectively additional breaks are added between -Inf and the lowest break and between the highest break and Inf.

mean

for draw_count, the mean number of count units for each observation

type

Type of Likert scale data for draw_likert. Valid options are 4, 5, and 7. Type corresponds to the number of categories in the Likert scale.

Details

For variables with intra-cluster correlations, see draw_binary_icc and draw_normal_icc

Value

A vector of data in accordance with the specification; generally numeric but for some functions, including draw_ordered, may be factor if break labels are provided.

Examples

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# Drawing binary values (success or failure, treatment assignment)
fabricate(N = 3,
   p = c(0, .5, 1),
   binary = draw_binary(prob = p))

# Drawing binary values with probit link (transforming continuous data
# into a probability range).
fabricate(N = 3,
   x = 10 * rnorm(N),
   binary = draw_binary(latent = x, link = "probit"))

# Repeated trials: `draw_binomial`
fabricate(N = 3,
   p = c(0, .5, 1),
   binomial = draw_binomial(prob = p, trials = 10))

# Ordered data: transforming latent data into observed, ordinal data.
# useful for survey responses.
fabricate(N = 3,
   x = 5 * rnorm(N),
   ordered = draw_ordered(x = x,
                          breaks = c(-Inf, -1, 1, Inf)))

# Providing break labels for latent data.
fabricate(N = 3,
   x = 5 * rnorm(N),
   ordered = draw_ordered(x = x,
                          breaks = c(-Inf, -1, 1, Inf),
                          break_labels = c("Not at all concerned",
                                           "Somewhat concerned",
                                           "Very concerned")))

# Likert data: often used for survey data
fabricate(N = 10,
          support_free_college = draw_likert(x = rnorm(N),
                                             type = 5))

# Count data: useful for rates of occurrences over time.
fabricate(N = 5,
   x = c(0, 5, 25, 50, 100),
   theft_rate = draw_count(mean=x))

# Categorical data: useful for demographic data.
fabricate(N = 6, p1 = runif(N), p2 = runif(N), p3 = runif(N),
          cat = draw_categorical(cbind(p1, p2, p3)))

DeclareDesign/fabricatr documentation built on May 6, 2019, 1:57 p.m.