A study is conducted to investigate whether living in a place with little sunlight can lead to depression. Researchers recruit two groups of 20 participants each from two locations. One group lives in Springbok, which experiences eight hours of sunlight daily during winter. The second group is recruited from Moscow, which experiences only four hours of sunlight daily during winter. On the winter solstice (the middle of winter), each group has their depression levels measured using a modified Beck Depression Inventory, which scores depression on a scale of 1 (no depression) to 10 (extreme depression). The following data are collected:
Springbok 2, 4, 3, 2, 2, 3, 2, 7, 1, 1, 2, 3, 2, 1, 6, 3, 4, 2, 3, 3
Moscow 5, 6, 7, 6, 6, 5, 8, 5, 2, 4, 1, 1, 7, 6, 9, 10, 8, 7, 9, 4
Are the researchers correct in suggesting that living with low levels of sunlight can lead to depression?