Tuesday, April 20, 2010

Baby Sleep Patterns

How do variables, such as number of naps during the day or time of sleep, affect the time Baby wakes up the next day?

Independent variables:
A - Number of naps during the day before
B - Total time (mins) napping the day before
C - Amount of time (mins) awake between last nap and sleep
D - Time of sleep
E - Amount of sleep (mins) that night
F - Amount of time (mins) awake during the night
G - Month

Dependent variable:
Time Baby wakes up

Overall results:
Independent variables are "Okay" at predicting when Baby wakes up. Results are useful to inform but not drive decisions. The effects are not statistically significant and models have mediocre predictive powers, probably due to other unaccounted confounding factors.

ANOVA results/discussions:
-Though, none of the variables had a statistically significant effect, factors C (amount of time awake between last nap and sleep) and F (amount of time awake during the night) tend to have the most effect on when Baby wakes up.
-Results could probably improve if I used time of sleep as a covariate ("future work" hehe).

Classification Tree results/discussions:
-Sleep time before or after 9:22pm has a big effect as to when Baby wakes up.
-If Baby is awake for more than 292.5 mins (4.9 hrs) before sleeping, Baby will tend to wake up later.
-As seem from the second graph below, this classification tree model tends to under-predict when Baby wakes up.

Neural Network results/discussions:
-Factors used in this model are "okay" as predicting when Baby wakes up.
-Test correlation was 0.88 which is pretty good. However, the overall performance was not great (R=0.5) probably due to over-training of the network.