Covariate balance is the extent to which the distribution of covariates is similar across the intervention groups.

## Standardized mean differences

The Standardized Mean Difference (SMD) represents a standardized difference in mean between contrasted intervention groups for each covariate.

| Means intervention group | Means control group | Standardized mean difference
--- | --- | --- | ---
distance | 0.89839344 | 0.89700714 | 0.125175777
age_cd | 11.59381714 | 11.58271865 | 0.003749979
sex_cd | 1.46657914 | 1.48366702 | -0.031811299
residence_area_cd731 | 0.13965147 | 0.14646997 | -0.019671111
residence_area_cd732 | 0.14108379 | 0.12961012 | 0.032960105
residence_area_cd733 | 0.71926474 | 0.72391992 | -0.010359603
institutionalized_blTRUE | 0.02781093 | 0.02950474 | -0.010301042
foreign_blTRUE | 0.15170685 | 0.12961012 | 0.061596004
pregnancy_blTRUE | 0.01181666 | 0.02107482 | -0.085675800
essential_worker_blTRUE | 0.02757221 | 0.02845100 | -0.005366853
comorbidities_blTRUE | 0.45977560 | 0.47523709 | -0.031023533
immunestatus_blTRUE | 0.28037718 | 0.26343519 | 0.037717288

| Means intervention group | Means control group | Standardized mean difference
--- | --- | --- | ---
distance | 0.50039178 | 0.49960822 | 0.0549503111
age_cd | 11.58454344 | 11.56054639 | 0.0081155840
sex_cd | 1.46431208 | 1.45286734 | 0.0212935144
residence_area_cd731 | 0.13942899 | 0.14398228 | -0.0131448309
residence_area_cd732 | 0.14078267 | 0.12453852 | 0.0467058195
residence_area_cd733 | 0.71978833 | 0.73147920 | -0.0260316250
institutionalized_blTRUE | 0.02768890 | 0.02670441 | 0.0060000891
foreign_blTRUE | 0.15185823 | 0.15161211 | 0.0006858036
pregnancy_blTRUE | 0.01193699 | 0.01021413 | 0.0158639539
essential_worker_blTRUE | 0.02781196 | 0.02756584 | 0.0014967947
comorbidities_blTRUE | 0.45975880 | 0.45791287 | 0.0037038685
immunestatus_blTRUE | 0.28058085 | 0.28144228 | -0.0019173492

## Variance ratios

The variance ratio (VR) represents the ratio of the variance in the contracted intervention groups for each covariate. A VR close to 1, implies that variances are similar in the compared groups and as such indicates good covariate balance.

| Var. Ratio
--- | ---
distance | 0.7576281
age_cd | 0.9708949
sex_cd | 0.9875230
residence_area_cd731 | NA
residence_area_cd732 | NA
residence_area_cd733 | NA
institutionalized_blTRUE | NA
foreign_blTRUE | NA
pregnancy_blTRUE | NA
essential_worker_blTRUE | NA
comorbidities_blTRUE | NA
immunestatus_blTRUE | NA

| Var. Ratio
--- | ---
distance | 1.0806187
age_cd | 0.9800742
sex_cd | 0.9590195
residence_area_cd731 | NA
residence_area_cd732 | NA
residence_area_cd733 | NA
institutionalized_blTRUE | NA
foreign_blTRUE | NA
pregnancy_blTRUE | NA
essential_worker_blTRUE | NA
comorbidities_blTRUE | NA
immunestatus_blTRUE | NA

## Propensity score distribution