smd_lgrr: Covariance between standardized mean difference and log risk...

Description Usage Arguments Value Author(s) References Examples

Description

Compute covariance between standardized mean difference and log risk ratio, when effect sizes are different.

Usage

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smd_lgrr(r,n1c,n2c,n1t,n2t,
         n12c=min(n1c,n2c),n12t=min(n1t,n2t),
         s2c,s2t,f2c,f2t,sd1c,sd1t)

Arguments

r

Correlation coefficient of the two outcomes.

n1c

Number of participants reporting outcome 1 in control group.

n2c

Number of participants reporting outcome 2 in control group.

n1t

Number of participants reporting outcome 1 in treatment group.

n2t

Number of participants reporting outcome 2 in treatment group.

n12c

Number of participants reporting both outcome 1 and outcome 2 in control group. By default, it is equal to the smaller number between n1c and n2c.

n12t

Number defined in a similar way as n12c for treatment group.

s2c

Number of participants with event for outcome 2 (dichotomous) in control group.

s2t

Defined in a similar way as s2c for treatment group

f2c

Number of participants without event for outcome 2 (dichotomous) in control group.

f2t

Defined in a similar way as f2c for treatment group

sd1c

Sample standard deviation of outcome 1.

sd1t

Defined in a similar way as sd1c for treatment group.

Value

Return the computed covariance.

Author(s)

Min Lu

References

Ahn, S., Lu, M., Lefevor, G.T., Fedewa, A. & Celimli, S. (2016). Application of meta-analysis in sport and exercise science. In N. Ntoumanis, & N. Myers (Eds.), An Introduction to Intermediate and Advanced Statistical Analyses for Sport and Exercise Scientists (pp.233-253). Hoboken, NJ: John Wiley and Sons, Ltd.

Wei, Y., & Higgins, J. (2013). Estimating within study covariances in multivariate meta-analysis with multiple outcomes. Statistics in Medicine, 32(7), 119-1205.

Examples

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## simple example
smd_lgrr(r=0.3,n1c=34,n2c=35,n1t=25,n2t=32,
         s2c=5,s2t=8,f2c=30,f2t=24,sd1t=0.4,sd1c=8)
## calculate covariances for variable SBP and DD in Geeganage2010 data
attach(Geeganage2010)
SBP_DD=unlist(lapply(1:nrow(Geeganage2010),function(i){smd_lgrr(r=0.3,
                 n1c=nc_SBP[i],n2c=nc_DD[i],n1t=nt_SBP[i],n2t=nt_DD[i],
                 sd1t=sdt_SBP[i],s2t=st_DD[i],sd1c=sdc_SBP[i],s2c=sc_DD[i],
                 f2c=nc_DD[i]-sc_DD[i],f2t=nt_DD[i]-st_DD[i])}))
SBP_DD

metavcov documentation built on May 2, 2019, 4:15 a.m.