Question: What is the highest sample size administered on October 18?
SQL: SELECT MAX("Sample size") FROM "2-16077776-1" WHERE "Date(s) administered" = 'October 18';

Question: What is the percentage for Mel Martinez when the sample size is 800?
SQL: SELECT "Mel Martinez (R)" FROM "2-16077776-1" WHERE "Sample size" = 800.0;