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Charting: Average Temperature After Ovulation - Stats Study

With this post I'd like to share with you a few stats results about average post-ovulatory temperatures (BBT) and pregnancy. These are preliminary results intended to give you some material for comments and feedback.

We looked at the average temperature between 1 and 10 Days Past Ovulation (DPO). The reason for looking particularly at this phase of the cycle is that we often see people looking at their average post-O temperatures as a potential early pregnancy sign.

For this study we have randomly selected a set of 1000 pregnancy charts and 1000 ovulatory charts (see the Chart Gallery for examples). For each chart we calculated the average temperature between 1 and 10 DPO.

The histogram below shows you the distribution of temperatures (in Fahrenheit) for pregnancy charts:

The histogram below shows you the distribution of temperatures (in Fahrenheit) for ovulatory charts:

In terms of more descriptive statistics here are a few interesting results:

Pregnancy Charts:
Average: 98.07F (36.71C)
Median: 98.10 (36.72C)
Standard Deviation: 0.28

Non Pregnant Charts:
Average: 98.04F (36.69C)
Median: 98.04F
Standard Deviation: 0.32

Statistically we did not find any strong evidence that the averages are different between the two samples (t-test for the stats wizzes among you).

That said the pregnancy histogram shows a difference with the non pregnant one in terms of standard deviation (the shape of the distribution is sharper on the pregnancy histogram compared to the non pregnant one).

Comments? Suggestions? Let me know.

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Posted: Aug 07, 2009 9:49am Eastern Time by Frederic, Founder.


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