I have a file that contains numeric values for dates (04131999). How do I change the numeric variables to date values (4/13/1999)?
There are a few ways to do this, but I would recommend using an informat statement with mmddyy for example: DATA SET2; SET SET1; DATE2 = INPUT(PUT(DATE1,8.),MMDDYY8.); FORMAT DATE2 MMDDYY8.; RUN;
Define active surveillance and provide an example.
Active surveillance-occurs when a health department is proactive and contacts health care providers or laboratories requesting information about diseases. While this method is more costly and labor intensive, it tends to provide a more complete estimate of disease frequency. For vaccine-preventable diseases, passive surveillance is the most common method, although active surveillance may be needed in special surveillance situations. Active surveillance is often short-term and usually requires more funding than passive surveillance. (ex: measles outbreak)
If a circle has the diameter of 8, what is the circumference?
The circumference of the circle is equal to pi multiplied by the diameter (C=pi * d). Substituting 8 for the diameter gives C=8π, where C is approximately 25.13.