Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What were the dates administered when the lead margin was larger than 14 and the poll source was Research 2000?

### Inputs:
table_name: table, columns: ['Poll Source', 'Dates administered', 'Democrat: Tom Harkin', 'Republican: Christopher Reed', 'Lead Margin']

### Response:
SELECT Dates administered FROM table WHERE Lead Margin > 14 AND Poll Source = research 2000