Sunday, August 21, 2011

A Small Google Search Bug

When you use the + prefix with Google search keywords, Google matches exact literal strings and does not return synonyms. If you search for spaghetti you can get a result for pasta, but if you search for +spaghetti you will only get spaghetti.

Should a Google search using the + prefix return more, fewer, or the same number of results as a search without the + prefix?

Here are a couple of possibilities:

1. The + prefix should return fewer results than the same query without the + operator: The + operator does not return synonyms, so if you search for keywords and their synonyms you should find a greater number of results pages.

2. The + prefix should return more results than the same query without the + operator: If searching for keywords and their synonyms requires more computational power than matching exact literal strings and if Google searches have time-out durations the +prefix keyword searches will return more results for any given amount of computational time.

The small bug is the discrepancy between these results:

1. Single keyword queries: + prefix returns fewer results.

2. Two keyword queries: + prefix returns more results.

Either the number of results feature is incompletely documented, making the metrics somewhat useless, or there's an algorithmic bug.

The examples below use arbitrary search keywords. In almost all cases, the + prefix returns fewer results for single keyword searches, but more results for two keyword searches.

Example #1:

About 556,000,000 results

About 534,000,000 results

About 212,000,000 results

About 204,000,000 results

pizza bicycle
About 17,200,000 results

+pizza +bicycle
About 53,100,000 results

pizza OR bicycle
About 727,000,000 results

+pizza OR +bicycle
About 1,440,000,000 results

Example #2:

About 939,000,000 results

About 903,000,000 results

About 756,000,000 results

About 729,000,000 results

coffee tea
About 75,900,000 results

+coffee +tea
About 120,000,000 results

coffee OR tea
About 1,630,000,000 results

+coffee OR +tea
About 3,160,000,000 results

Example #3:

About 276,000,000 results

About 269,000,000 results

About 102,000,000 results

About 99,300,000 results

ant caterpillar
About 6,350,000 results

+ant +caterpillar
About 16,700,000 results

ant OR caterpillar
About 365,000,000 results

+ant OR +caterpillar
About 731,000,000 results

Example #4:

About 621,000,000 results

About 575,000,000 results

About 1,400,000,000 results

About 1,290,000,000 results

baseball football
About 321,000,000 results

+baseball +football
About 325,000,000 results

baseball OR football
About 1,860,000,000 results

+baseball OR +football
About 3,610,000,000 results

Example #5:

About 38,000,000 results

About 37,200,000 results

About 167,000,000 results

bout 163,000,000 results

crayon pencil
About 8,260,000 results

+crayon +pencil
About 8,480,000 results

crayon OR pencil
About 399,000,000 results

+crayon OR +pencil
About 398,000,000 results