movStats: movStats

View source: R/movStats.r

movStatsR Documentation

movStats

Description

Moving Estimates Using Overlapping Windows

Usage

movStats(
  formula,
  stat = NULL,
  discrete = FALSE,
  space = c("n", "x"),
  eps = if (space == "n") 15,
  varyeps = FALSE,
  nignore = 10,
  xinc = NULL,
  xlim = NULL,
  times = NULL,
  tunits = "year",
  msmooth = c("smoothed", "raw", "both"),
  tsmooth = c("supsmu", "lowess"),
  bass = 8,
  span = 1/4,
  maxdim = 6,
  penalty = NULL,
  trans = function(x) x,
  itrans = function(x) x,
  loess = FALSE,
  ols = FALSE,
  qreg = FALSE,
  lrm = FALSE,
  orm = FALSE,
  hare = FALSE,
  lrm_args = NULL,
  family = "logistic",
  k = 5,
  tau = (1:3)/4,
  melt = FALSE,
  data = environment(formula),
  pr = c("none", "kable", "plain", "margin")
)

Arguments

formula

a formula with the analysis variable on the left and the x-variable on the right, following by optional stratification variables

stat

function of one argument that returns a named list of computed values. Defaults to computing mean and quartiles + N except when y is binary in which case it computes moving proportions. If y has two columns the default statistics are Kaplan-Meier estimates of cumulative incidence at a vector of times.

discrete

set to TRUE if x-axis variable is discrete and no intervals should be created for windows

space

defines whether intervals used fixed width or fixed sample size

eps

tolerance for window (half width of window). For space='x' is in data units, otherwise is the sample size for half the window, not counting the middle target point.

varyeps

applies to space='n' and causes a smaller eps to be used in strata with fewer than “ observations so as to arrive at three x points

nignore

see description, default is to exclude nignore=10 points on the left and right tails from estimation and plotting

xinc

increment in x to evaluate stats, default is xlim range/100 for space='x'. For space='n' xinc defaults to m observations, where m = max(n/200, 1).

xlim

2-vector of limits to evaluate if space='x' (default is nignore smallest to nignore largest)

times

vector of times for evaluating one minus Kaplan-Meier estimates

tunits

time units when times is given

msmooth

set to 'smoothed' or 'both' to compute lowess-smooth moving estimates. msmooth='both' will display both. 'raw' will display only the moving statistics. msmooth='smoothed' (the default) will display only he smoothed moving estimates.

tsmooth

defaults to the super-smoother 'supsmu' for after-moving smoothing. Use tsmooth='lowess' to instead use lowess.

bass

the supsmu bass parameter used to smooth the moving statistics if tsmooth='supsmu'. The default of 8 represents quite heavy smoothing.

span

the lowess span used to smooth the moving statistics

maxdim

passed to hare, default is 6

penalty

passed to hare, default is to use BIC. Specify 2 to use AIC.

trans

transformation to apply to x

itrans

inverse transformation

loess

set to TRUE to also compute loess estimates

ols

set to TRUE to include rcspline estimate of mean using ols

qreg

set to TRUE to include quantile regression estimates w rcspline

lrm

set to TRUE to include logistic regression estimates w rcspline

orm

set to TRUE to include ordinal logistic regression estimates w rcspline (mean + quantiles in tau)

hare

set to TRUE to include hazard regression estimtes of incidence at times, using the polspline package

lrm_args

a list of optional arguments to pass to lrm when lrm=TRUE, e.g., list(maxit=20)

family

link function for ordinal regression (see rms::orm)

k

number of knots to use for ols and/or qreg rcspline

tau

quantile numbers to estimate with quantile regression

melt

set to TRUE to melt data table and derive Type and Statistic

data

data.table or data.frame, default is calling frame

pr

defaults to no printing of window information. Use pr='plain' to print in the ordinary way, ⁠pr='kable⁠ to convert the object to knitr::kable and print, or pr='margin' to convert to kable and place in the Quarto right margin. For the latter two results='asis' must be in the chunk header.

Details

Function to compute moving averages and other statistics as a function of a continuous variable, possibly stratified by other variables. Estimates are made by creating overlapping moving windows and computing the statistics defined in the stat function for each window. The default method, space='n' creates varying-width intervals each having a sample size of 2*eps +1, and the smooth estimates are made every xinc observations. Outer intervals are not symmetric in sample size (but the mean x in those intervals will reflect that) unless eps=nignore, as outer intervals are centered at observations nignore and n - nignore + 1 where the default for nignore is 10. The mean x-variable within each windows is taken to represent that window. If trans and itrans are given, x means are computed on the trans(x) scale and then itrans'd. For space='x', by default estimates are made on to the nignore smallest to the nignore largest observed values of the x variable to avoid extrapolation and to help getting the moving statistics off on an adequate start for the left tail. Also by default the moving estimates are smoothed using supsmu. When melt=TRUE you can feed the result into ggplot like this: ⁠ggplot(w, aes(x=age, y=crea, col=Type)) + geom_line() +⁠ facet_wrap(~ Statistic)

See here for several examples.

Value

a data table, with attribute infon which is a data frame with rows corresponding to strata and columns N, Wmean, Wmin, Wmax if stat computed N. These summarize the number of observations used in the windows. If varyeps=TRUE there is an additional column eps with the computed per-stratum eps. When space='n' and xinc is not given, the computed xinc also appears as a column. An additional attribute info is a kable object ready for printing to describe the window characteristics.

Author(s)

Frank Harrell


Hmisc documentation built on June 22, 2024, 12:19 p.m.