*Technical Footnote: Regarding the CRABI 12-Month-Old Dummy

Summary: The harness slot height you choose in a car seat should depend on the length of the baby’s torso, i.e. the seated shoulder height, rather than the weight of the baby. While the CRABI 12-Month-Old regulated crash test dummy is the maximum overall weight and height allowed in the Orbit Infant Car Seat, it only has an average seated shoulder height.  As such, our Infant Car Seat is designed with top shoulder harness slots to accommodate children with torsos longer than that of the CRABI 12, and still fall under the maximum weight and height restrictions of the seat.  Any assertions that the top shoulder slot is appropriate for the CRABI 12 (because this dummy represents the maximum overall weight and height allowed in our Infant Car Seat) show an incomplete understanding of the facts and technical issues involved.

 

The CRABI 12-Month-Old (or CRABI 12) crash test dummy is the standard dummy used in FMVSS 213 compliance testing.  The CRABI 12 weighs 22 lbs and is 29.5” in height, which are the "largest child" weight and height dimensions allowed in the Orbit Baby Infant Car Seat. The middle slot of the Infant Car Seat is appropriate for the CRABI 12, and the technical reasons why there is a higher slot position on the seat are explained below.

The history of the CRABI 12 is that it is based on several large samplings of child anthropometric data conducted by the University of Michigan Transportation Research Institute (Report 85-23 in 1985).  The SAE (Society of Automotive Engineers) took the measurement data for the one-year-old children and used the mean (average) measurements of this data to specify the measurements of the CRABI 12 dummy.  For example, the mean for one-year-old seated height (seated height to the top of the head) is 18.9”, and this is therefore also the seated height of the CRABI 12. However, the actual data of seated height measurements of one-year-old children range from 16.9” up to 21.3”, with a standard deviation of 0.9”. 

Because we want our Infant Car Seat to accommodate a reasonable range of real-life one-year-old children, we have worked with car seat experts to determine that a car seat should accommodate children with measurements 2 standard deviations away from the average measurement (95% of the population), which translates into a maximum seated height of 20.7” (18.9” + 0.9” + 0.9” = 20.7”).

As a responsible car seat manufacturer, we have to assume that there are children who fall into these extreme parts of the range (in this case, having a long torso but being average weight), especially since the study referenced above does not establish a correlation between weight and seated height (e.g., a 22 lb child could well have a long seated height of 20.7”).

In conclusion, while the Orbit Infant Car Seat's middle shoulder harness slot is the appropriate position for the CRABI 12 dummy (which represents the average one-year-old's seated height of 18.9"), the Orbit Infant Car Seat's top harness slot is the appropriate position for children with longer-than-average torsos, that fall under 2 standard deviations from the average seated height (20.7").

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