Random-Effects Model (k = 23; tau^2 estimator: REML)

tau^2 (estimated amount of total heterogeneity): 68.8997 (SE = 37.0805)
tau (square root of estimated tau^2 value):      8.3006
I^2 (total heterogeneity / total variability):   60.88%
H^2 (total variability / sampling variability):  2.56

Test for Heterogeneity: 
Q(df = 22) = 52.8276, p-val = 0.0002

Model Results:

estimate       se     zval     pval    ci.lb    ci.ub          
-67.3022   2.3624 -28.4885   <.0001 -71.9325 -62.6719      *** 

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Signif. codes:  0 *** 0.001 ** 0.01 * 0.05 . 0.1   1 