or2smd function

Conversion from log odds ratio to standardised mean difference

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

or2smd(
  lnOR,
  selnOR,
  studlab,
  data = NULL,
  subset = NULL,
  exclude = NULL,
  method = "HH",
  ...
)

Arguments

• lnOR: Log odds ratio(s) or meta-analysis object.
• selnOR: Standard error(s) of log odds ratio(s) (ignored if argument lnOR is a meta-analysis object).
• studlab: An optional vector with study labels (ignored if argument lnOR is a meta-analysis object).
• data: An optional data frame containing the study information (ignored if argument lnOR is a meta-analysis object).
• subset: An optional vector specifying a subset of studies to be used (ignored if argument lnOR 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 lnOR is a meta-analysis object).
• method: A character string indicating which method is used to convert log odds ratios to standardised mean differences. Either "HH" or "CS", can be abbreviated.
• ...: Additional arguments passed on to metagen (ignored if argument lnOR is a meta-analysis object).

Returns

An object of class c("metagen", "meta") with corresponding generic functions (see meta-object).

Details

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

• 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 standardised mean difference as summary measure.

Argument lnOR can be either a vector of log odds ratios or a meta-analysis object created with metabin or metagen and the odds ratio as summary measure.

Argument selnOR is mandatory if argument lnOR is a vector and ignored otherwise. Additional arguments in ...

are only passed on to metagen if argument lnOR

is a vector.

Examples

# Example from Borenstein et al. (2009), Chapter 7
#
mb <- or2smd(0.9069, sqrt(0.0676))
# TE = standardised mean difference (SMD); seTE = standard error of SMD
data.frame(SMD = round(mb$TE, 4), varSMD = round(mb$seTE^2, 4))

# Use dataset from Fleiss (1993)
#
data(Fleiss1993bin)
m1 <- metabin(d.asp, n.asp, d.plac, n.plac,
  data = Fleiss1993bin, studlab = paste(study, year),
  sm = "OR", random = FALSE)
or2smd(m1)

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

See Also

smd2or, metabin, metagen, metacont

Author(s)

Guido Schwarzer guido.schwarzer@uniklinik-freiburg.de