Note that Epiphany dates the 2009 survey to around March, while the other two surveys happened around November, so inputting the survey dates just as years lowballs the time gap between the first & second surveys. Your linear trend’ll be a bit exaggerated.
Before, the slope per year was −2.24 (minus 2.25 points a year), now the slope spits out as −0.00519 but if I’m understanding my changes right, the unit has switched from per year to per day and 365.25 times −0.005 IQ points per day is −1.896 per year.
To add a linear model (for those unfamiliar, see my HPMoR examples) which will really just recapitulate the simple averages calculation:
Note that Epiphany dates the 2009 survey to around March, while the other two surveys happened around November, so inputting the survey dates just as years lowballs the time gap between the first & second surveys. Your linear trend’ll be a bit exaggerated.
I’ve fixed it as appropriate.
Before, the slope per year was −2.24 (minus 2.25 points a year), now the slope spits out as −0.00519 but if I’m understanding my changes right, the unit has switched from per year to per day and 365.25 times −0.005 IQ points per day is −1.896 per year.
2.25 vs 1.9 is fairly different.