Simple Random Sample Survey Design

A survey design object for equal-probability simple random samples — surveys where every unit had an equal chance of selection and there is no clustering or stratification. Create via as_survey() with no ids, strata, or fpc arguments.

Usage

survey_srs(
  data = data.frame(),
  metadata = survey_metadata(),
  variables = list(),
  groups = character(0),
  call = NULL
)

Arguments

data

A data.frame containing the survey data. Prefer as_survey() over calling this constructor directly.

metadata

A survey_metadata object. Created automatically by as_survey().

variables

A named list of design specification. Set automatically by as_survey().

groups

Set by surveytidy's group_by(). Always character(0) in standalone surveycore use.

call

Language object capturing the construction call.

Value

A survey_srs object.

When to use this class

Use survey_srs (via as_survey(df) or as_survey(df, weights = w) with no design structure) when:

• The sample was drawn by simple random sampling (every unit equally likely to be selected)

• There are no clusters or strata to specify

• You want the standard SRS variance formula: s²/n × (1 - f) where f = n/N is the sampling fraction (0 when population size is unknown)

For non-probability samples or post-hoc calibrated weights (raking, post-stratification, propensity matching), use as_survey_calibrated() instead.

For complex probability samples with known design structure (PSUs, strata), use as_survey() with ids, strata, and/or fpc — which creates a survey_taylor object.

Design variables (@variables)

weights

Character string naming the weight column, or NULL for uniform weights (all equal; auto-generated as "..surveycore_wt..").

probs_provided

Logical. TRUE if the user supplied sampling probabilities rather than weights.

fpc

Character string naming a finite population correction column, or NULL. When NULL, assumes infinite population (f = 0).

fpc_type

Character string: "population" when the FPC column contains population sizes (values > 1), "fraction" when it contains sampling fractions (values in (0, 1]), or NULL when no FPC is specified.

ids

Always NULL. SRS has no cluster structure.

strata

Always NULL. SRS has no stratification.

nest

Always FALSE.

See also

as_survey_srs() to create a survey_srs object directly; as_survey() for Taylor series designs.

Other constructors: as_survey(), as_survey_calibrated(), as_survey_rep(), as_survey_srs(), as_survey_twophase(), survey_calibrated(), survey_data(), survey_replicate(), survey_taylor(), survey_twophase()