How to ignore the first line of data when processing CSV data?

You could use an instance of the csv module's Sniffer class to deduce the format of a CSV file and detect whether a header row is present along with the built-in next() function to skip over the first row only when necessary:

import csv

with open('all16.csv', 'r', newline='') as file:
    has_header = csv.Sniffer().has_header(file.read(1024))
    file.seek(0)  # Rewind.
    reader = csv.reader(file)
    if has_header:
        next(reader)  # Skip header row.
    column = 1
    datatype = float
    data = (datatype(row[column]) for row in reader)
    least_value = min(data)

print(least_value)

Since datatype and column are hardcoded in your example, it would be slightly faster to process the row like this:

    data = (float(row[1]) for row in reader)

Note: the code above is for Python 3.x. For Python 2.x use the following line to open the file instead of what is shown:

with open('all16.csv', 'rb') as file:

To skip the first line just call:

next(inf)

Files in Python are iterators over lines.

Borrowed from python cookbook,
A more concise template code might look like this:

import csv
with open('stocks.csv') as f:
    f_csv = csv.reader(f) 
    headers = next(f_csv) 
    for row in f_csv:
        # Process row ...