# md_rd: Computing Covariance between Mean Difference and Risk... In metavcov: Computing Variances and Covariances, Visualization and Missing Data Solution for Multivariate Meta-Analysis

 md_rd R Documentation

## Computing Covariance between Mean Difference and Risk Difference

### Description

The function `lgor_rd` computes covariance between mean difference and risk difference. See `mix.vcov` for effect sizes of the same or different types.

### Usage

``````md_rd(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 the control group. `n2c ` Number of participants reporting outcome 2 in the control group. `n1t ` Number of participants reporting outcome 1 in the treatment group. `n2t ` Number of participants reporting outcome 2 in the treatment group. `n12c ` Number of participants reporting both outcome 1 and outcome 2 in the 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 the treatment group. `s2c ` Number of participants with event for outcome 2 (dichotomous) in the control group. `s2t ` Defined in a similar way as `s2c` for the treatment group. `f2c ` Number of participants without event for outcome 2 (dichotomous) in the control group. `f2t ` Defined in a similar way as `f2c` for the treatment group. `sd1c ` Sample standard deviation of outcome 1 for the control group. `sd1t ` Defined in a similar way as `sd1c` for the treatment group.

### Value

 `rd` Computed risk difference for outcome 2. `v` Computed covariance.

Min Lu

### References

Lu, M. (2023). Computing within-study covariances, data visualization, and missing data solutions for multivariate meta-analysis with metavcov. Frontiers in Psychology, 14:1185012.

### Examples

``````## a simple example
md_rd(r = 0.71, 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){md_rd(r = 0.71,
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])\$v}))
SBP_DD
## the function mix.vcov() should be used for dataset
``````

metavcov documentation built on July 9, 2023, 7:11 p.m.