Fix error in burden assoc when using BBeta weights

BBeta weights should not be inverted, otherwise common variants will end
up being weighted higher than rare variants

raremetal/src/Meta.cpp

@@ -3564,9 +3564,11 @@ void Meta::BurdenAssoc(String method, GroupFromAnnotation &group, Vector *&maf,
         weight.Dimension(maf[g].Length());
         SetWeight(method, weight, maf[g]);
         // for burden test, need to 1/w
-        for (int w = 0; w < weight.Length(); w++)
-        {
+        // if using BBeta weighting, the weights should not be inverted (otherwise, common variants will end up with higher weights)
+        if (method != "BBeta") {
+          for (int w = 0; w < weight.Length(); w++) {
             weight[w] = 1 / weight[w];
+          }
         }
 
         numerator = weight.InnerProduct(stats[g]);