Hacker News new | ask | show | jobs
by kacesensitive 431 days ago
A 0.060 standard deviation improvement is super small. If the average person rates their happiness/anxiety/depression score at, say, 50 out of 100, and the standard deviation (how spread out people’s scores are) is around 10 points, then 0.060 SD = 0.6 points. So quitting Facebook gave an average person a ~1% bump in mood score. Instagram was even smaller: ~0.4 points, or 0.8%.

It's real, but barely noticeable for most people—unless you're in a more affected subgroup (e.g. undecided voters or younger women). Your experience feeling way better likely means you were an outlier (in a good way).
2 comments
mmooss 431 days ago
On what scale? What do 'points' on the scale mean? Without knowing those things, we can't say what 6 or 60 points mean.
link
blackbear_ 431 days ago
On the contrary, reporting changes relative to the standard deviation of a control group frees you from scales and their meanings, because it relates the observed change to the normal spread of scores before the intervention. In this way, you don't need to know the scale and its meaning to know if a change is big or small, and from a statistical perspective, that's (almost) all you need to find if a change is significant or due to random chance. Of course, looking back at the original scale and its meaning can help interpreting the meaning of the results in other ways
link
mmooss 430 days ago
Standard deviation helps, but you still need to know: standard deviation of what? It's no different than saying someone scored 78% - 78% of what? What is it in the denominator? Also, different scales can represent the same thing differently.

Secondly, the impact of the difference isn't known - you don't know the curve representing the relationship of score to impact. In some contexts a little change is meaningless - the curve is flat; in others the curve is steep and it can be transformational. And impacts only sometimes scale linearly with performance or score, of course.

Without that knowledge, standard deviation means nothing beyond how unusual, in the given population, the subject's performance is.

link
perching_aix 431 days ago
This is what I was interested in, thank you!
link