BY-COVID - WP5 - Baseline Use Case: COVID-19 vaccine effectiveness assessment

Matching cases to controls (1:1) and assessing covariate balance after matching

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