The old way

Manual category boost

List of words

Word	    CategoryId	Boost
===========================
iphone	    2601	1
iphone	    340186	1
iphone 4s   340186	1
iphone 5    340186      1
iphone 4    340186	1

How is a match found

For each word in category list
  if word is contained in query
    use this category

Examples

Query: iphone
    
Word	    CategoryId	Is match
===========================
iphone	    2601	yes
iphone	    340186	yes
iphone 4s   340186	yes
iphone 5    340186      yes
iphone 4    340186	yes


Query: 4s
    
Word	    CategoryId	Is match
===========================
iphone	    2601	no
iphone	    340186	no
iphone 4s   340186	no
iphone 5    340186      no
iphone 4    340186	no

Algorithmic Problems

• Short words in list might match long words
• Long words in list no match in query
• Term based -> lower precision 

iphone skal -> boost on iphone

New way

We will test three variants

The simple

• For top 1500 boost categories with more than 80% of conversions in that category
• Do this in each level of the category tree
• High category boost

Characteristics

• Only boost when sure of winner
• Will not find categories to boost for all queries

The Advanced

• For top 1500 searches boost based on percentage of conversion in that category
• Do this for all levels
• Lower boost levels

Characteristics

• Always boost                                               
• Can cloak equally good categories
• Categories will matter less

The middle

• For top 1500 searches boost top 3 categories in level if winner is > 80%
• Do this for all levels
• High category boost

Characteristics

• Only boost when sure of winner
• Will not find categories to boost for all queries