scdf {scan}

Single case data frame

Description

scdf() is the constructor for the scdf class. It stores single-case study data with one or more single-cases.

Usage

scdf(
  values,
  B_start,
  mt,
  phase,
  phase_design = NULL,
  phase_starts = NULL,
  name = NULL,
  dvar = "values",
  pvar = "phase",
  mvar = "mt",
  ...
)

Arguments

values

A vector containing measurement values of the dependent variable.

B_start

The first measurement of phase B (simple coding if design is strictly AB).

mt

A vector defining measurement times. Default is ⁠mt = (1,2,3,...,n)⁠.

phase

A vector defining phase assignments.

phase_design

A list defining the length and label of each phase. E.g., phase_design = c(A1 = 10, B1 = 10, A2 = 10, B2 = 10).

phase_starts

A vector defining the label and measurement time of each phase start. E.g., phase_starts = c(A1 = 1, B1 = 6, A2 = 14, B2 = 19).

name

A name for the case.

dvar

Character string with the name of the dependent variable. Defaults to the attributes in the scdf file.

pvar

Character string with the name of the phase variable. Defaults to the attributes in the scdf file.

mvar

Character string with the name of the measurement time variable. Defaults to the attributes in the scdf file.

...

Additional variables. E.g., ⁠teacher = c(0,1,0,1,0,0,1), lesson = c(1,3,4,5,2,3)⁠.

Details

If the dependent variable is a named vector then the names are extracted to create a phase design (e.g., values = c(A = 2,3,5,4,3, B = 6,5,4,3) will create an AB phase design with five and four measurements). An scdf contains several attributes: dvar The name of the dependent variable. phase The name of the phase variable. mt The name of the measurement time variable. author Information on the author of the data. info Further information on the data. E.g., a publication. ⁠dvar, phase⁠, and mt are the defaults most of the scan function use. You can change the values of the attributes with the scdf_attr function (e.g., scdf_attr(exampleAB_add, "dvar") <- "depression" defines depression as the dependent variable. Please notice that all scan functions have arguments to define dvar, phase, and mt for a given analysis.

Value

Returns a single-case data frame scdf suitable for all functions of the scan package. Multiple data sets (e.g. from Multiple Baseline Designs) can be listed.

Author(s)

Juergen Wilbert

See Also

Other data manipulation functions: add_l2(), as.data.frame.scdf(), as_scdf(), fill_missing(), moving_median(), outlier(), ranks(), select_cases(), set_vars(), shift(), smooth_cases(), standardize(), truncate_phase()

Examples

## Scores on a letter naming task were collected on eleven days in a row.
## The intervention started after the fifth measurement,
## so the first B phase measurement was 6 (B_start = 6).
klaas <- scdf(
  c(5, 7, 8, 5, 7, 12, 16, 18, 15, 14, 19),
  B_start = 6, name = "Klaas"
)
describe(klaas)

# Alternative coding 1:
klaas <- scdf(
  c(A = 5, 7, 8, 5, 7, B = 12, 16, 18, 15, 14, 19),
  name = "Klaas"
)

# Alternative coding 2:
klaas <- scdf(
  c(5, 7, 8, 5, 7, 12, 16, 18, 15, 14, 19),
  phase_design = c(A = 5, B = 6), name = "Klaas"
)

## Unfortunately in a similar study there were no data collected on
## days 3 and 9. Use NA to pass them to the function:
emmi <- scdf(c(5, 7, NA, 5, 7, 12, 16, 18, NA, 14, 19),
  phase_design = c(A = 5, B = 6), name = "Emmi"
)
describe(emmi)

## In a MBD over three cases, data were collected eleven days in a row.
## Intervention starting points differ between subjects as they were
## randomly assigned. The three SCDFs are then combined in a list for
## further conjoined analyses.
charlotte <- scdf(c(A = 5, 7, 10, 5, 12, B = 7, 10, 18, 15, 14, 19))
theresa <- scdf(c(A = 3, 4, 3, 5, B = 7, 4, 7, 9, 8, 10, 12))
antonia <- scdf(c(A = 9, 8, 8, 7, 5, 7, B = 6, 14, 15, 12, 16))
mbd <- c(charlotte, theresa, antonia)
names(mbd) <- c("Charlotte", "Theresa", "Antonia")
overlap(mbd)

## In a classroom-based intervention it was not possible to measure outcomes
## every day, but only on schooldays. The sequence of measurements is passed
## to the package by using a vector of measurement times.
frida <- scdf(
  c(A = 3, 2, 4, 2, 2, 3, 5, 6, B = 8, 10, 8, 12, 14, 13, 12),
  mt = c(1, 2, 3, 4, 5, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18)
)
summary(frida)
describe(frida)

## example with two independent variables and four phases
jim <- scdf(
  zvt = c(47, 58, 76, 63, 71, 59, 64, 69, 72, 77, 76, 73),
  d2 = c(131, 134, 141, 141, 140, 140, 138, 140, 141, 140, 138, 140),
  phase_design = c(A1 = 3, B1 = 3, A2 = 3, B2 = 3), dvar = "zvt"
)
overlap(jim, phases = list(c("A1", "A2"), c("B1", "B2")))