meta: smd2or – R documentation

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smd2or

Conversion from standardised mean difference to log odds ratio

Description

Conversion from standardised mean difference to log odds ratio using method by Hasselblad & Hedges (1995) or Cox (1970).

Usage

smd2or(
  smd,
  se.smd,
  studlab,
  data = NULL,
  subset = NULL,
  exclude = NULL,
  method = "HH",
  backtransf = gs("backtransf"),
  ...
)

Arguments

`smd`	Standardised mean difference(s) (SMD) or meta-analysis object.
`se.smd`	Standard error(s) of SMD (ignored if argument `smd` is a meta-analysis object).
`studlab`	An optional vector with study labels (ignored if argument `smd` is a meta-analysis object).
`data`	An optional data frame containing the study information (ignored if argument `smd` is a meta-analysis object).
`subset`	An optional vector specifying a subset of studies to be used (ignored if argument `smd` is a meta-analysis object).
`exclude`	An optional vector specifying studies to exclude from meta-analysis, however, to include in printouts and forest plots (ignored if argument `smd` is a meta-analysis object).
`method`	A character string indicating which method is used to convert SMDs to log odds ratios. Either `"HH"` or `"CS"`, can be abbreviated.
`backtransf`	A logical indicating whether odds ratios (if TRUE) or log odds ratios (if FALSE) should be shown in printouts and plots.
`...`	Additional arguments passed on to `metagen` (ignored if argument `smd` is a meta-analysis object).

Details

This function implements the following methods for the conversion from standardised mean difference to log odds ratio:

Hasselblad & Hedges (1995) assuming logistic distributions (method == "HH")
Cox (1970) and Cox & Snell (1989) assuming normal distributions (method == "CS")

Internally, metagen is used to conduct a meta-analysis with the odds ratio as summary measure.

Argument smd can be either a vector of standardised mean differences or a meta-analysis object created with metacont or metagen and the standardised mean difference as summary measure.

Argument se.smd is mandatory if argument smd is a vector and ignored otherwise. Additional arguments in ... are only passed on to metagen if argument smd is a vector.

Value

An object of class "meta" and "metagen"; see metagen.

Author(s)

Guido Schwarzer sc@imbi.uni-freiburg.de

References

Borenstein M, Hedges LV, Higgins JPT, Rothstein HR (2009): Introduction to Meta-Analysis. Chichester: Wiley

Cox DR (1970): Analysis of Binary Data. London: Chapman and Hall / CRC

Cox DR, Snell EJ (1989): Analysis of Binary Data (2nd edition). London: Chapman and Hall / CRC

Hasselblad V, Hedges LV (1995): Meta-analysis of screening and diagnostic tests. Psychological Bulletin, 117, 167–78

Examples

# Example from Borenstein et al. (2009), Chapter 7
#
mb <- smd2or(0.5, sqrt(0.0205), backtransf = FALSE)
# TE = log odds ratio; seTE = standard error of log odds ratio
data.frame(lnOR = round(mb$TE, 4), varlnOR = round(mb$seTE^2, 4))

# Use dataset from Fleiss (1993)
#
data(Fleiss1993cont)
m1 <- metacont(n.psyc, mean.psyc, sd.psyc, n.cont, mean.cont, sd.cont,
               data = Fleiss1993cont, sm = "SMD",
               studlab = paste(study, year))
smd2or(m1)