scdf: Single case data frame

In scan: Single-Case Data Analyses for Single and Multiple Baseline Designs

Single case data frame

Description

scdf() is the constructor for objects of class scdf. It stores data from single-case studies with one or more cases in a structured format suitable for analysis with the scan package.

Usage

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

Arguments

...	One or more vectors representing measurement variables. See the Details section.
B_start	The first measurement point of phase B (simple coding; only applicable if the design follows a strict AB pattern).
phase_starts	A named vector defining the label and measurement time of each phase start. For example: phase_starts = c(A1 = 1, B1 = 6, A2 = 14, B2 = 19).
phase_design	A named vector defining the length and label of each phase. For example: phase_design = c(A1 = 10, B1 = 10, A2 = 10, B2 = 10).
name	Optional 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.

Details

If no variable matching the name of the dependent variable is provided (the default name is values, which can be changed via the dvar argument), and the first provided variable is unnamed, that variable will be interpreted as the dependent variable.

If no measurement-time variable is provided (default name mt, configurable via the mvar argument), measurement times are automatically defined as a sequence ⁠(1, 2, 3, ..., n)⁠.

If the dependent variable is a named vector, the names will be used to define a phase design. For example, values = c(A = 2, 3, 5, 4, 3, B = 6, 5, 4, 3) will be interpreted as an AB phase design with five measurements in phase A and four in phase B.

If a vector matching the name of the phase variable is provided, it will be used to define the phase design directly.

Value

Returns a single-case data frame scdf suitable for all functions in the scan package.

Author(s)

Juergen Wilbert

See Also

Other data manipulation functions: add_l2(), as.data.frame.scdf(), as_scdf(), fill_missing(), moving_median(), outlier(), ranks(), rescale(), 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: using named vector
klaas <- scdf(
  c(A = 5, 7, 8, 5, 7, B = 12, 16, 18, 15, 14, 19),
  name = "Klaas"
)

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

# Alternative: using phase_starts
klaas <- scdf(
  c(5, 7, 8, 5, 7, 12, 16, 18, 15, 14, 19),
  phase_starts = c(A = 1, B = 7), 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))
tonia <- scdf(c(A = 9, 8, 8, 7, 5, 7, B = 6, 14, 15, 12, 16))
mbd <- c(charlotte, theresa, tonia)
names(mbd) <- c("Charlotte", "Theresa", "Tonia")
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")))

scan documentation built on June 29, 2025, 5:08 p.m.