Tuesday, April 22, 2008

Our Growing Boy

Grant had his 6-month visit today. Here are the stats from his 4-month visit:

Weight: 14.2 lbs. (38%)
Height: 24 in. (20%)
Head Circumference: 16.1 in. (21%)

Here are the changes:
Weight: 17 lbs. (37%)
Height: 25.8 in. (22%)
Head Circumference: 17.2 in. (48%)

The nurse even measured his head twice to make sure there wasn't a mistake in the measurement. The kid's head grew a ton! To put it in math terms: his weight and height follow a logarithmic trend, his head circumference is linear! What do you guys think?


Candace said...

So I'm sure your question is more rhetorical, but here is my math-nerd answer: How can you tell what kind of trend it is with only two data points? The others could be linear too, just with smaller slopes. Plus, you probably want the head to have a logarithmic trend so that the size eventually levels off. If you have a plot of his past measurements, you should make a plot of them and really test your hypotheses. And if you really want to have some math-stat fun, you could fit a cubic smoothing spline nonparametric function to the data--cool.

On a less math-nerdy note: Thank you, thank you for the pictures and update.

Nathaniel & Tenille said...

Yeah, we should post the data and you can do the hypothesis test for differences between the regression functions of his head and body growth.