95% ci

#1
Hi I am trying to interpret a journal article about the results of whether drinking cokes leads to child hyperactivity, the sample taken from a group of children where there are three sub groups as: never drink, drink 1-2 times/week and more than 1-2 times/week
the baseline is set at those who never drink.
The result goes as follows:

Hyperactivity:
Never 13.4
Light 10.1
Heavy 12.6

I want to know why when they calculate the OR, using the never group as baseline, the OR for light group 0.73 (0.58 to 0.91) and the OR for heavy is 0.92 (0.61 to 1.39). What I got for light group is 10.1/13.4 = 0.75 and for heavy group was 12.6/13.4 = 0.94

Also, how to they calculate the CI?
Thanks
 

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Ninja say what!?!
#2
It's weird that they would calculate OR's, when RR's would be fine here. What you calculated was the RR (relative risk). Odds ratios are calculated as the ratio of Odds, which requires probabilities (or odds) of an event. There's probably something you're missing.