SmartSwitch Bid Request Weight

SmartSwitch uses predictive analysis to decrease the amount of traffic that has a low chance of winning an impression being sent to the target Buyer. In order to achieve this, SmartSwitch evaluates a bid request and assigns a Score to it. The Score in this context means the chances of the Buyer winning the impression.

The probability of a bid request being sent to a Buyer depends on the chances of it winning an impression. The values range from 100% for High Impression Win Probability traffic, to 5% or less for Low Impression Win Probability.

From the perspective of all parties in the system, it is important that every single bid request has some chance of being passed to the Buyer. This means that the Buyer sees all possible traffic segments, even though some are more represented than the others.

However, from the Buyer‘s perspective it is hard to tell “the SmartSwitch calculated value” of any specific bid request that BidSwitch sends, and therefore two questions arise from this situation:

  • Is it true that we win impressions mostly in High Impression Win Probability traffic, and rarely in Low Impression Win Probability traffic?
  • How much traffic is SmartSwitch filtering out?

To enable Buyers to calculate this for themselves, the ext.wt field is passed in the Bid Request. Use the information below to understand how this field can be used to calculate how SmartSwitch impacts your traffic.

Bid Request Weight Field

SmartSwitch Bid Weight Property Values
Field Type Description Example
ext.wt float

Shows the total number of bid requests with the same SmartSwitch Score that this Bid Request represents.

This number can be used to calculate the amount of traffic of this type that would be received if SmartSwitch were turned off. Any bid request that you receive with this weight (X) is highly likely to be sent X times without SmartSwitch filtering.

When this field value equals 1, there are no unsent bid requests with a matching score.


Bid Weight Use Case


  • A Buyer receives 10 bid requests from BidSwitch (Request ID Column)
  • Each Bid Request has a weight attributed to it (Request Weight Column). This represents the value set in the ext.wt field.
  • The Buyer Bids on requests #102 - #107, winning all except #106 (Impression Won Column), meaning they won 5/6 bids
Weighted Value Use Case
Request ID Request Weight Buyer Bid Impression Won Clearing Price CPM Click
101 5 No      
102 1 Yes Yes $1 No
103 1 Yes Yes $0.5 No
104 2 Yes Yes $0.2 No
105 1 Yes Yes $1.3 Yes
106 10 Yes No    
107 1 Yes Yes $0.8 No
108 1 No      
109 1 No      
110 7 No      
Total Sent: 10 Potentially Sent: 30 Total Bids: 6 Total Wins: 5 Total CPM: $3.80 Total clicks: 1

The above numbers can be interpreted as follows:

  • The total number of bid requests that were available to be sent to the Buyer was 30
    • This figure is calculated by adding the Request Weight column, 5+1+1+2+1+10+1+1+1+7 = 30
    • 20 of these Bid Requests were filtered out by SmartSwitch. This is calculated by subtracting the total sent from the potentially sent, Potentially Sent - Total Sent = The Total SmartSwitch Filtered Out
  • Without SmartSwitch, the Buyer would have won 6 impressions, (4 wins @weight=1 + 1 win @weight=2), for $4 CPM ($1.3 + $1 + $0.8 + $0.5 + ($0.2 * 2)) = $4 and have 1 click.
    • Hint: Impression #104 had Request Weight = 2 and a media cost of $0.2 CPM, meaning that without SmartSwitch there would have been two impression here for the total of $0.4 CPM.
  • SmartSwitch Impact
    • SmartSwitch saved 66% (20/30) of traffic processing
    • At the cost of missing 16% (1/6) of impression wins and 5% ($0.2/$4) of media spend
    • With no click losses

Google AdX Analogy

AdX also shapes Buyer traffic using a feature called Selective Callouts. When a traffic segment is shaped, AdX sends only 5% of that traffic and every bid request in that segment has a flag is_predicted_to_be_ignored set to true.

In BidSwitch terminology, bid requests with is_predicted_to_be_ignored=false have weight=1 and is_predicted_to_be_ignored=true have weight=20.

Example Bid Request with Bid Weight

An example Bid Request with the SmartSwitch Bid Weight Value.

      "ua":"Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.85 Safari/537.3",
         "city":"La Jolla",