premise: The Okanagan Highland is an elevated hilly plateau area in British Columbia, Canada, and the U.S. state of Washington (where it is spelled Okanogan Highlands). Rounded mountains with elevations up to 8,000 feet above sea level and deep, narrow valleys are characteristic of the region.
hypothesis: Equal numbers use the spelling Okanagan Highland versus Okanogan Highlands.
reason: Actually, it is uncertain [but doubtful] that EQUAL NUMBERS use the different spellings, but it is not stated. The model was confused because the spellings are used by two different groups.