declare_measurement {DeclareDesign} | R Documentation |

This function adds measured data columns that can be functions of unmeasured data columns.

```
declare_measurement(..., handler = measurement_handler, label = NULL)
measurement_handler(data, ...)
```

`...` |
arguments to be captured, and later passed to the handler |

`handler` |
a tidy-in, tidy-out function |

`label` |
a string describing the step |

`data` |
A data.frame. |

It is also possible to include measured variables in your declare_model call or to add variables using declare_step. However, putting latent variables in declare_model and variables-as-measured in declare_measurement helps communicate which parts of your research design are in M and which parts are in D.

A function that returns a data.frame.

```
# declare_measurement in use
## Two-arm randomized experiment
design <-
declare_model(
N = 500,
X = rep(c(0, 1), each = N / 2),
U = rnorm(N, sd = 0.25),
potential_outcomes(Y ~ 0.2 * Z + X + U)
) +
declare_inquiry(ATE = mean(Y_Z_1 - Y_Z_0)) +
declare_sampling(S = complete_rs(N = N, n = 200)) +
declare_assignment(Z = complete_ra(N = N, m = 100)) +
declare_measurement(Y = reveal_outcomes(Y ~ Z)) +
declare_estimator(Y ~ Z, inquiry = "ATE")
# Reveal potential outcomes according to treatment assignment
design <-
declare_model(N = 100,
potential_outcomes(Y ~ rbinom(
N, size = 1, prob = 0.1 * Z + 0.5
))) +
declare_assignment(Z = complete_ra(N, m = 50)) +
declare_measurement(Y = reveal_outcomes(Y ~ Z))
# Generate observed measurement from a latent value
design <-
declare_model(N = 100, latent = runif(N)) +
declare_measurement(observed = rbinom(N, 1, prob = latent))
# Index creation
library(psych)
design <-
declare_model(
N = 500,
X = rep(c(0, 1), each = N / 2),
Y_1 = 0.2 * X + rnorm(N, sd = 0.25),
Y_2 = 0.3 * X + 0.5 * rnorm(N, sd = 0.50),
Y_3 = 0.1 * X + 0.4 * rnorm(N, sd = 0.75)) +
declare_measurement(
index = fa(
r = cbind(Y_1, Y_2, Y_3),
nfactors = 1,
rotate = "varimax"
)$scores
)
draw_data(design)
```

[Package *DeclareDesign* version 1.0.2 Index]