- n
The level-1 sample size per level-2 unit.
- p
The proportion of level-1 units within each level 2 unit
to be assigned to treatment.
- icc
The unconditional intraclass correlation coefficient (ICC) in population or in
each treatment condition.
- r12
The proportion of level-1 variance explained by covariates.
- r22m
The proportion of variance of site-specific treatment
effect explained by covariates.
- c1
The cost of sampling one level-1 unit in control condition.
- c2
The cost of sampling one level-2 unit (site).
- c1t
The cost of sampling one level-1 unit in treatment condition.
- omega
The standardized variance of site-specific treatment effect.
- m
Total budget, default is the total costs of sampling 60
sites.
- plots
Logical, provide variance plots if TRUE, otherwise not; default value is TRUE.
- plot.by
Plot the variance by n and/or p;
default value is plot.by = list(n = "n", p = "p").
- nlim
The plot range for n, default value is c(2, 50).
- plim
The plot range for p, default value is c(0, 1).
- varlim
The plot range for variance, default value is c(0, 0.05).
- nlab
The plot label for n,
default value is "Level-1 Sample Size: n".
- plab
The plot label for p,
default value is "Proportion Level-1 Units in Treatment: p".
- varlab
The plot label for variance,
default value is "Variance".
- vartitle
The title of variance plot, default value is NULL.
- verbose
Logical; print the values of n
and p if TRUE, otherwise not; default value is TRUE.
- iter
Number of iterations; default value is 100.
- tol
Tolerance for convergence; default value is 1e-10.
- q
The number of covariates at level 2. Default is 1.
- d
Standardized effect size, default is 0.1.
- power
Statistical power.
- aco
Logic. If TRUE, the function will use the ant colony
optimization (ACO) algorithm to identify optimal allocations. If FALSE,
the function will use the first-order derivative method to identify
optimal allocations. Default is TRUE.
- d.p
The initial sampling domains for p. Default is c(0.1, 0.5).
- d.n
The initial sampling domain for n. Default is c(2, 1000).
- sig.level
Significance level or type I error rate, default value is 0.05.
- two.tailed
Logical; two-tailed tests if TRUE,
otherwise one-tailed tests; default value is TRUE.
- Jlim
The range for solving the root of level-2 sample size
(J) numerically. Change the default values to a larger range
(e.g., starting with a smaller value) if
f() values at end points are not of opposite sign. For example,
use Jlim = c(1.5, 1e10).
- nrange
The range of the level-1 sample size per level-2 unit
that used to exclude unreasonable values. Default value is c(2, 10000).
- max.value
Maximal value of optimization when used as
the stopping criterion. Default is -Inf.
- max.iter
Maximal number of function evaluations when used as
the stopping criterion.
- e
Maximum error value used when solution quality used as
the stopping criterion, default is 1e-10.
- n.of.ants
Number of ants used in each iteration after the initialization
of power analysis for calculating required budget, default value is 10.
- n.of.archive
Size of the solution archive, default is 100.
- q.aco
Locality of the ACO search (0,1), default is 0.0001.
- xi
Convergence pressure (0, Inf), suggested: (0, 1), default is 0.5.