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_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_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, the latent data for each observation.

breaks

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

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

The number of buckets to split data into. For a median split, enter 2; for terciles, enter 3; for quartiles, enter 4; for quintiles, 5; for deciles, 10.

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.

Details

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

Examples


# Drawing binary values (success or failure, treatment assignment)
fabricate(N = 3,
   p = c(0, .5, 1),
   binary = draw_binary(prob = p))
#>   ID   p binary
#> 1  1 0.0      0
#> 2  2 0.5      0
#> 3  3 1.0      1

# 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"))
#>   ID          x binary
#> 1  1   2.557354      1
#> 2  2 -11.789878      0
#> 3  3  -7.021686      0

# Repeated trials: `draw_binomial`
fabricate(N = 3,
   p = c(0, .5, 1),
   binomial = draw_binomial(prob = p, trials = 10))
#>   ID   p binomial
#> 1  1 0.0        0
#> 2  2 0.5        4
#> 3  3 1.0       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)))
#>   ID          x ordered
#> 1  1 -0.4480415       2
#> 2  2  1.1573840       3
#> 3  3 -0.3886420       2

# 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")))
#>   ID         x              ordered
#> 1  1  1.701911       Very concerned
#> 2  2 -3.840224 Not at all concerned
#> 3  3  0.315974   Somewhat concerned


# 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))
#>   ID   x theft_rate
#> 1  1   0          0
#> 2  2   5          6
#> 3  3  25         28
#> 4  4  50         50
#> 5  5 100         93

# 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)))
#>   ID        p1         p2         p3 cat
#> 1  1 0.4410702 0.16962063 0.02071859   1
#> 2  2 0.7369205 0.20115172 0.85366067   1
#> 3  3 0.9815113 0.00863554 0.73225794   1
#> 4  4 0.4019670 0.72577925 0.93173699   3
#> 5  5 0.7157953 0.36336891 0.75901858   1
#> 6  6 0.1646743 0.92153621 0.13260611   1