Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_19948664_1 (countries_sampled INTEGER, ranking_la__2_ VARCHAR, author___editor___source VARCHAR, year_of_publication VARCHAR)

### Question ###
How many countries were sampled in the index created by The Economist, published in 2007 and ranked 2nd in the LA Ranking?

### Accurate SQL ###

SELECT MAX(countries_sampled) FROM table_19948664_1 WHERE author___editor___source = "The Economist" AND year_of_publication = "2007" AND ranking_la__2_ = "2nd"