Table: senate_polls_2004
Columns: poll_source
date_s_administered
sample_size
margin_of_error
mel_martinez_r
betty_castor_d

Question: What is the highest sample size administered on October 18?
SQL: SELECT MAX("sample_size") FROM senate_polls_2004 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 senate_polls_2004 WHERE "sample_size" = 800