score = (x) -> 
  if x == "Yes"
    10
  else
    0
  
weights = [0.25, 0.25, 0.25, 0.25]
invasive_alien_spieces = [introduction_risk, introduction_risk_in_value_chain, introduction_disclosure, introduction_prevention]

weights.reduce((weighted_sum, weight, index) -> 
              weighted_sum + weight*score(invasive_alien_spieces[index])
             , 0)