Monday, January 29, 2018

Statistic on Age When Diabetes is First Diagnosed

Age When Diabetes is First Diagnosed

Question:  What is the typical age when people are first diagnosed with diabetes?

Why might a presentation of means and standard deviations mislead the reader?

The MEPs sample has an upper limit on age of 85.   People over 85 are listed as 85.   What effect does the top-coding of age have on the distribution of the age when diabetes is first diagnosed?

The Medical Expenditures Panel Survey does not have information on whether the person has type one or type two diabetes.   Why might this lack of information on type one versus type two information mislead the reader?

Some Summary Statistics Describing the Age People are First Diagnosed with Diabetes:

 Some Statistics on Age of First  Diagnosis for Diabetes o% 1% 11 5% 23 10% 30 25% 40 50% 50 75% 59 90% 67 95% 71 99% 80 100% 85 Mean 48.7 Std 14.5 Skewness -0.24 Kurtosis 3

Discussion:

Around 50 percent of diabetics are first diagnosed between age 40 and age 58.

Around 5 percent of diabetics are first diagnosed when under age 23.

Another 5 percent of diabetics are first diagnosed when they are 71 years old or over.

The max age on the MEPS database is 85. The top coding of the age variable shortens the upper tail of the age distribution.  The top coding reduces estimated kurtosis.

The tails of the distribution, especially the lower tail, are quite large.  The reported mean and even the reported inter-quartile distribution do not accurately display information on the size of the tails.

Type One and Type Two Diabetes are two different diseases with different causes.   Most Type One Diabetics are diagnosed when they are very young.   Most diabetics are type two.

The MEPs database combines information about both type one and type two diabetes.   The age of first diagnosis for type 2 diabetes is a bit older than the ages implied by the combined sample.  The inclusion of type 1 diabetics in the sample is the reason for the large lower tail.

Authors Note:  Readers in this post might also be interested in this post on disease and workforce participation for people 62 and over.

Readers might also be interested in article on obesity and diabetes