Data-frame Object has no Attribute

Check your DataFrame with data.columns

It should print something like this

Index([u'regiment', u'company',  u'name',u'postTestScore'], dtype='object')

Check for hidden white spaces..Then you can rename with

data = data.rename(columns={'Number ': 'Number'})

I'm going to take a guess. I think the column name that contains "Number" is something like " Number" or "Number ". Notice that I'm assuming you might have a residual space in the column name somewhere. Do me a favor and run print "<{}>".format(data.columns[1]) and see what you get. Is it something like < Number>? If so, then my guess was correct. You should be able to fix it with this:

data.columns = data.columns.str.strip()