Bit late on the post, but IMHO, if the wall runs parallel to the joists, it is unlikely to be load bearing, particularly if it does not continue directly up on the first floor. sIf it does carry on to the 1st floor ceiling joists it is probably carrying some roof weight and would require an rsj .
Essentially if it is parallel to the floor joists and goes no higher than th g/f ceilng, or just above it cannot be load bearing and is simply a partition.
You do not give the age of the house, as methods varied from period to period, ie Victorian, 30's, 70's etc.
Hope this is of somehelp
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