AIDS Data Animation Project:
Explanation of Methodology


Creation of GIF Images

Still frames were created using the SAS (r), SAS Institute, Inc., software package. Initially code was written using SAS/Graph (r) processing weekly data into a single image. The code was then turned into a macro format and invoked for each weeks' worth of data. Following evaluation of initial output, a procedural format was decide upon and the GIF images were turned into MPEG format for animation pruposes. Several of these still frames are presented. The final GIF files were 1200 x 900 pixels.

Creation of MPEG Animations

For each of the animations, GIF files for weeks 26 through 626, inclusive, were processed on a dual-processor Sun SPARCstation 20 computer operating under Solaris 2.4. The files were first processed using various software filters provided as part of the Portable Bitmap Toolkit, in order to:

Most of the filters were invoked by a single Bourne shell script.

The resulting collection of of ppm files was then subjected to MPEG-1 encoding using software developed by Prof. Lawrence Rowe and his colleagues at the University of California, Berkeley. The pattern of MPEG frame types used was: IBBPBBI, and the remaining configuration parameters were as follows: GOP_SIZE=6, SLICES_PER_FRAME=1, PIXEL=HALF, RANGE=10, PSEARCH_ALG=LOGARITHMIC, BSEARCH_ALG=CROSS2, IQSCALE=8, PQSCALE=10, BQSCALE=25, and REFERENCE_FRAME=ORIGINAL.

Each set of files was processed twice, producing large (592 x 448 pixel) and small (288 x 224 pixel) images.

Creation of Video Animations

A video animation of the AIDS mortality data is also available from Dr. Robin Lake at (rbl@hal.cwru.edu) Environmental Modeling Inc. The video segments which comprise this video are the same national and regional animations as presented here --- plus a single-state animation for Ohio.

These animations were produced by downloading 600 individual GIFs from the NIH FTP site and transfering each set of GIFs to a Macintosh Quadra 900 computer. The shareware application GraphicConverter was then used to create a QuickTime movie at 320 by 240 pixel resolution, with no compression. Peter's Player was used to display the resulting QuickTime movie with settings to assure that each frame of the movie was presented.

The video output of the Macintosh monitor was fed into a Folsom "Otto" video converter, with zoom adjusted to fill the video frame. Videos were then recorded on a Mitsubishi Super-VHS video cassette recorder or a SONY U-Matic-S video recorder.

Selected QuickTime movies were also played back in 24-bit color on a Stardent TITAN workstation, with video fed through the Folsom video converter and recorded as with the Macintosh.


U.S. Map Data Aggregations

Non-aggregate Data

In their simplest version (US-non aggregate), stills were created for each week in the 13-year period. Stills show the age-, sex-, and race-adjusted AIDS mortality for each county for the one year period around the week of interest (six months forward and back). All non-zero rates from all stills were ordered and the events were divided into 64ths of rank; these were assigned the color spectrum shown on the bottom bar.

Small-County Aggregate Data

Because confidentiality agreements required not reporting rates derived from counts less than three, and because there were many such observations, the US-non aggregate animation may underestimate the progression of AIDS mortality in rural areas. To compensate for this potential bias, two forms of aggregation were used. In the animation labled US small county aggregate, All counties within a state with counts of 0, 1, or 2 AIDS deaths were lumped and their combined rate was calculated and colored.

State Economic Areas

Because confidentiality agreements required not reporting rates derived from counts less than three, and because there were many such observations, the US-non aggregate animation may underestimate the progression of AIDS mortality in rural areas. To compensate for this potential bias, two forms of aggregation were used. In the animation labled "US State Economic Areas" counties were combined as defined by this standardized classification and colored.


Regional Map Data Aggregation

Central States

The states appearing here include: Michigan, Ohio, West Virginia, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas, Missouri, Illinois, Indiana, Wisconsin, Minnesota, Iowa, Nebraska, South Dakota, North Dakota, Montana, Wyoming, Colorado, New Mexico, Arizona, Utah, Idaho.

Gulf States

The states appearing here include: Texas, Louisiana, Arkansas, Mississippi, Alabama, Florida.

Midatlantic States

The states appearing here include: Maryland, Delaware, Distric of Columbia, Virginia.

Northeastern States

The states appearing here include: Pennsylvania, New Jersey, New York, Connecticut, Massachussets, Rhode Island, Vermont, New Hampshire, Maine.

Southeastern States

The states appearing here include: Florida, Georgia, South Carolina, North Carolina, Maryland, Delaware, Distric of Columbia, Virginia.

Western States

The states appearing here include: California, Nevada, Oregon, Washington.
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