The LEXIS Computer Program for Creating Shaded Contour Maps of Demographic Surfaces

W O R K I N G P A P E R

The LFXIS C o m p u t e r Program for C r e a t i n g S h a d e d C o n t o u r -Yaps of D e m o g r a p h i c Surf aces

B r a d l e y A. G a m b i l l Jams W. V a u p e l Anatoli I Y a s h i n

A u g u s t 1 9 8 6 W-86-037

lnternat~onal lnstltute for Appl~ed Systems Analys~s

A-2361 LaxenburgIAustr~a

W _{I IASA}

NOT FOR QUOTATION WITHOUT THE PERMISSION OF THE AUTHORS

The LMIS Computer Program for Creating Shaded Contour Maps of Demographic Surfaces

B r a d l e y A. GambiLL James W. VaupeL AnatoLi I. Y a s h i n

August 1986 WP-86-37

Working P a p e r s are interim r e p o r t s on work of t h e International I n s t i t u t e f o r Applied Systems Analysis and h a v e r e c e i v e d only limited review. V i e w s o r opinions e x p r e s s e d h e r e i n d o ' n o t n e c e s s a r i l y r e p r e s e n t t h o s e of t h e Institute o r of its National Member Organizations.

INTERNATIONAL INSTITUTE FOR APPLIED SYSTEMS ANALYSIS 2361 Laxenburg, Austria

Tke

LEUS

Computer Program Tor Creating Shaded Contour Maps

oT Demo~raphic Suriaces

B r a d l e y A. Gumbill*, James W. VaupeL**, Anatoli I. Yashine**

The LEXIS computer program, which w a s developed at t h e International Insti- t u t e for Applied Systems Analysis (IIASA) and Duke University, i s intended to aid demographers in t h e analysis of l a r g e a r r a y s of data. I t s application as a supple- ment t o o t h e r methods of g r a p h i c display is demonstrated in T h o u s a n d s of Data a t a GLance: Shaded Contour Maps of PopuLation Surfaces (Vaupel. Gambill, and Yashin, forthcoming) and will not b e discussed h e r e . This p a p e r provides instruc- tions on t h e use of t h e program, gives some hints concerning t h e art and craft of using t h e program in a c r e a t i v e way, and briefly d e s c r i b e s t h e algorithm used in designing t h e program. A d i s k e t t e containing a copy of t h e LEXIS program is en- closed. The program i s copyrighted but t h e d i s k e t t e is not p r o t e c t e d against copy- ing: please feel free t o make and d i s t r i b u t e copies. By making t h e program avail- a b l e t o demographers and o t h e r s i n t e r e s t e d in mapping t h e contours of s u r f a c e s , w e hope t o encourage t h e development of t h i s method of d a t a analysis. W e would, of c o u r s e , s i n c e r e l y a p p r e c i a t e i t if w e and t h e International Institute f o r Applied Systems Analysis were acknowledged when t h e program o r some modified version of i t is used t o p r o d u c e maps for presentation or publication. Comments and sugges- tions are welcome!

*Bradley A. Cambill, T. Rowe P r i c e A s s o c i a t i o n , 100 E a s t P r a t t S t r e e t , Baltimore, Maryland 21202, USA

**James W. Vaupel, Humphrey institute o f Public A f f a i r s , U n i v e r s i t y of Minnesota, 301 19th Avenue South, Minneapolis, MN 55455, USA

***Anatolf 1. Yashin, Population Program, IlASA, A-2361 Laxenburg, Austria

ADDRESS COMMENTS TO: Bradley A. Gambill, T. Rowe P r i c e Association, 100 E a s t P r a t t S t r e e t , Baltimore, Maryland 21202, USA o r to James W . Vaupel, Humphrey In- s t i t u t e of Public Affairs, University of Minnesota, 3 0 1 1 9 t h Avenue South, Minneap- olis, Minnesota 55455, USA.

ADDRESS REQUESTS FOR ADDITIONAL OR UPDATED COPIES OF THE PROGRAM TO:

e i t h e r of t h e above o r to Information S e r v i c e s , Population Program, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria.

USE OF THE PROGRAM Important Preliminaries

I t will b e assumed throughout t h i s p a p e r t h a t t h e r e a d e r h a s some knowledge of t h e IBM p e r s o n a l computer and t h e DOS operating system. If t h i s i s not t h e case, w e recommend t h a t a potential u s e r of t h e LEXIS program review t h e DOS manual provided with h i s or h e r IBM or IBM-compatible p e r s o n a l computer. Because t h e program d o e s v e r y little input/output checking, such knowledge may b e quite help- ful.

The d i s k e t t e accompanying t h e p a p e r contains two files: LX.COM and USFERT.

The use of t h e program will b e discussed s h o r t l y , but i t i s important t h a t t h e pro- gram b e copied to a d i s k e t t e formated by t h e u s e r ' s computer to include t h e DOS system for convenience. W e recommend t h a t t h e original d i s k e t t e and a backup copy b e s t o r e d in a safe place.

Printing H a p s from the Screen

To p r i n t a LEXIS map from t h e computer s c r e e n , you must e n t e r GRAPHICS (using y o u r original DOS diskette) at t h e

>

DOS prompt b e f o r e beginning t h e LEXIS program. Once t h e s u r f a c e h a s been completely drawn on t h e s c r e e n , e n t e r t h e

<shift> and < P r t S c > keys simultaneously to p r i n t t h e map.

Format of Input Data

The d a t a t o b e used by t h e LEXIS program must b e in ASCII format, with nz re- petitions of a p a t t e r n consisting of t h e value of a label (such as t h e c u r r e n t y e a r ) followed by n d a t a items (such as mortality rates at various ages). The value of n must b e l e s s than 150 and t h e value of m must b e l e s s t h a n 300. For example, t o plot a s u r f a c e of mortality rates q (a , t ) from a g e 0 t o 99 and y e a r 1900 t o 1982 t h e f i r s t d a t a e n t r y in t h e input file would b e 1900, t h e second e n t r y q(0,1900), t h e t h i r d e n t r y q (1,1900), and s o on up t o t h e 1 0 l s t e n t r y which would b e q (99,1900).

The 102nd e n t r y would b e 1901, followed by q(0,1901), a n d s o on up through q(99,1901). This p a t t e r n would b e r e p e a t e d up through t h e y e a r 1982; t h e v e r y l a s t e n t r y being q (99,1982). The label does not have t o b e a y e a r : i t could b e a n a g e o r a life-expectancy o r t h e value of any o t h e r v a r i a b l e t h a t d e s c r i b e s t h e data. Similarly, t h e successive d a t a values following t h e label d o not have t o p e r - tain t o successive y e a r s of a g e , but could p e r t a i n t o successive values of any o t h e r v a r i a b l e t h a t d e s c r i b e s t h e second dimension of t h e data. In any c a s e , with input d a t a in this format, t h e map will have t h e n - v a r i a b l e (e.g., a g e ) on t h e y-axis, t h e nz-variable (e.g., y e a r ) on t h e z-axis, and t h e d a t a values (e.g., t h e q 's) as t h e t h i r d dimension r e p r e s e n t e d in t h e map.

Zeroes may b e used t o r e p r e s e n t missing values in t h e d a t a , if t h e a c t u a l d a t a r a n g e does not include z e r o . This use of z e r o s i s discussed below.

Beginning the

LEXIS

Program

To begin t h e LEXIS program, simply t y p e LX at t h e DOS prompt. A t i t l e s c r e e n will a p p e a r at t h e start of t h e program and d i s a p p e a r after a few seconds, leaving t h e Main Menu on t h e s c r e e n .

Main Menu Options

A: Initializing data files

A l l d a t a t o b e mapped must f i r s t b e initialized by t h e LEXIS program. The pro- c e d u r e consists simply of entering t h e dimensions of t h e d a t a file, and, optionally, searching t h e d a t a f o r i t s highest and lowest points. This p r o c e d u r e begins with t h e selection of option A from t h e Main Menu. The u s e r i s prompted t o e n t e r t h e name and disk d r i v e of t h e input d a t a file, as well as t h e disk d r i v e of t h e output file. The initialization p r o c e s s c r e a t e s a file with t h e same p r e f i x as t h e input file, and extension .SPF. The information contained in t h e .SPF file is provided by t h e

u s e r of t h e LEXIS program, as described in t h e next s t e p below. A list of t h e r e - quired information will a p p e a r on t h e s c r e e n , and t h e c u r s o r will move from place t o place t o prompt t h e u s e r t o e n t e r t h e a p p r o p r i a t e numbers. The s c r e e n will ap- p e a r as follows (with illustrative numbers in bold print).

Notice t h a t t h e x-axis information must b e e n t e r e d f i r s t , then t h e y-axis in- formation. In o u r example of a mortality surface, w e would e n t e r t h e year-axis in- formation, followed by t h e age-axis information. Once all necessary information has been e n t e r e d , t h e program will ask if t h e d a t a should b e s e a r c h e d f o r t h e high and low. If y is e n t e r e d , LEXIS will p r i n t t h e label (e.g., y e a r ) of t h e f i r s t column on t h e s c r e e n , followed by t h e label of each successive column. Checking t h e column labels as they a p p e a r on t h e s c r e e n is a n excellent way t o b e s u r e t h a t t h e d a t a is in t h e p r o p e r format, and contains t h e p r o p e r number of e n t r i e s in each d a t a column. Once t h e initialized file is created. i t i s stored on t h e diskette and i s available f o r all f u t u r e mapping.

B: Selecting D i s p l a y C o l o r s

Selection of display colors is optional, with background color zero, line color z e r o , and a standard s c r e e n p a t t e r n being t h e default settings. An experienced u s e r of t h e LEXIS program will find t h e selection of display colors t o b e a powerful option, however. By selecting this option, t h e u s e r is able t o s e l e c t background color, line color, and p a t t e r n t o b e used in creating t h e map. The choice of back- ground color is self-explanatory, and is a matter of personal taste f o r t h e user.

The selection of line color depends on t h e d a t a and t h e user's goals: if t h e lines are an important p a r t of t h e map, they should b e drawn in a color different than those used t o c r e a t e t h e p a t t e r n s displayed (yellow f o r t h e p r i n t p a t t e r n s , back- ground f o r t h e s c r e e n patterns). If t h e e x a c t location of t h e lines is less impor- t a n t than t h e general t r e n d s of change within t h e surface, then i t may b e more in- formative t o hide t h e lines by making them t h e color of t h e most dominant color of t h e p a t t e r n s being used. Experimentation w i l l allow t h e u s e r t o determine which combinations of color will provide t h e most effective presentation of data.

The selection of p a t t e r n is a very powerful option provided by t h e LEXIS pro- gram. Included in t h e program are two sets of color combination p a t t e r n s o r

"palettes"

-

t h e "screen" p a t t e r n s which fade from green t o yellow t o r e d , and t h e

"print" p a t t e r n s which use t h e colors necessary t o produce a p p r o p r i a t e shades of gray when a contour map is printed on a n IBM o r Epson p r i n t e r . The s c r e e n pat- t e r n s are probably most pleasing t o t h e eye, and provide distinguishable shades of

logically progressing colors on a color s c r e e n ; t h e p r i n t p a t t e r n s provide t h e most easily distinguishable p a t t e r n s when displayed on t h e p r i n t e r o r most monochrome monitors. It is possible t o alter t h e s e p a t t e r n s by entering 3 f o r p a t t e r n color and then placing a 1, 2 o r 3 next t o t h e a p p r o p r i a t e region when prompted t o d o so. We have found i t useful t o shade r a t i o s u r f a c e s with just t h r e e colors, one represent- ing the a r e a below 1 , one t h e region approximately equal t o 1 , and t h e last t h e re- gion above 1. Other examples of use of this option are included in Vaupel, Gambill and Yashin. (1985); experimentation will help a u s e r decide which color p a t t e r n s lead t o t h e most informative maps.

C: C r e a t i n g a m a p from a data f i l e

Once all preliminary initializations and selections a r e completed, a map can b e c r e a t e d by selecting t h e C option from t h e Main Menu. The s u r f a c e creation menu will a p p e a r and prompt t h e u s e r chose a single d a t a s e t map, a map developed from taking t h e r a t i o of two d a t a sets, o r a map c r e a t e d by taking t h e difference of two d a t a sets. Once a selection is made, a new menu a p p e a r s on t h e s c r e e n :

CFY> FiLes

To e n t e r t h e name(s) of t h e input file(s) select t h e <F1> option when t h e bot- tom s c r e e n menu is highlighted. Since only one file is t o be used in creating t h e map, only one input prompt will be given. If two files are t o b e used, t h e initial prompt will b e f o r t h e numerator o r minuend filename, and t h e second prompt f o r t h e denominator o r subtrahend file f o r r a t i o and difference surfaces, respective- ly.

If t h e map will include only one data s e t , t h e u s e r will b e asked if t h e actual data include zeroes. If t h e d a t a r a n g e includes zero, then "Y" should b e e n t e r e d at this prompt. If, however. z e r o e s are used only t o denote missing values, in cohort d a t a f o r example, then t h e u s e r should e n t e r "N" o r <return>. For r a t i o surfaces, division by z e r o will b e set equal t o t h e background color.

<F2

>

^{a e c s}

The next s t e p in creating a map is t o e n t e r t h e size of t h e s u r f a c e t o b e displayed. The program will display t h e file specifications of each input file used in creating t h e s u r f a c e , and then prompt t h e u s e r t o e n t e r specifications f o r t h e map t o b e c r e a t e d . If t h e e n t i r e d a t a set is t o b e mapped, i t is not necessary t o select this option. For comparative purposes. t h e dimensions may b e extended beyond t h e b o r d e r s of t h e d a t a set in t h e z direction. In t h i s case t h e missing d a t a

values will b e assigned t h e background c o l o r G 3 > S m o o t h i n g

Next, t h e u s e r will b e asked if t h e s u r f a c e should b e smoothed. If smoothing i s d e s i r e d , t h e u s e r must e n t e r a n odd number l e s s t h a n or equal to twenty-one. The smoothing p r o c e d u r e simply r e p l a c e s e a c h point in t h e s u r f a c e with t h e weighted a v e r a g e of t h e points in t h e n by n s q u a r e surrounding t h e point. F o r example, if n is five, 25 points surrounding t h e original point will b e a v e r a g e d using t h e fol- lowing weights :

When a point i s n e a r a boundary, t h e weighted a v e r a g e is t a k e n o v e r a l l t h o s e points within t h e surrounding s q u a r e f o r which d a t a are available.

<F4

>

L i n e s

Line selection i s p e r h a p s t h e m o s t important decision t h a t must b e made in c r e a t i n g a shaded c o n t o u r map. The LEXIS program provides seven d i f f e r e n t op- tions f o r selecting t h e b e s t lines:

U > M o r t a l i t y

-

Mortality s u r f a c e lines begin with .000667 and t h e n i n c r e a s e by 50% from o n e line t o t h e next. W e found t h e s e intervals to b e useful in drawing contour maps of mortality s u r f a c e s . The contours are placed at t h e following lev- els:

(2> F e r t i l i t y

-

Fertility s u r f a c e lines are placed at i n t e r v a l s w e found t o b e convenient when analyzing f e r t i l i t y s u r f a c e s :

(3> Ratio

-

Ratio lines a r e placed at levels we sometimes found useful when analyzing s u r f a c e s t h a t r e p r e s e n t e d t h e r a t i o of two s u r f a c e s (e.g., male vs. female mortality). Each contour is 1 0 p e r c e n t g r e a t e r than t h e previous contour, as fol- lows:

<4> Dineerence

-

The difference lines option allows t h e u s e r t o e n t e r high and low values f o r a surface. The program then calculates t h e levels of 1 5 lines .between t h e two points. These lines, depending on t h e u s e r ' s choice, are placed e i t h e r at even multiples o r even intervals.

<5> MuLtipLes

-

Even multiple lines option allows t h e u s e r t o e n t e r a begin-

ning point, and a multiplier. The f i r s t line is placed at t h e beginning point and t h e o t h e r lines are spaced at even multiples of t h e multiplier given. Thus, if 1.1 is t h e given multiplier, t h e lines increase by 1 0 p e r c e n t , starting at t h e beginning point.

(6> Auto-SeLect

-

The a u t o select lines option t a k e s t h e high and t h e low of t h e input file, and places 15 lines between t h e two points. The lines are placed at even multiples o r even intervals, depending on t h e user's response t o a prompt.

<7> Selected

-

The selected lines option allows t h e u s e r t o place t h e lines at any desired locations.

Once t h e lines have been chosen, e n t e r <8> E z i t t o r e t u r n t o t h e menu at t h e bottom of t h e s c r e e n .

UB

>

Menu

Entering function key 5 will r e t u r n t h e u s e r t o t h e main menu of t h e LEXIS program.

U%> Map

A f t e r all necessary information has been entered, t h e <F6> key can b e used t o start producing t h e map on t h e s c r e e n . The process can b e interrupted only by re-booting t h e system. The last s t e p in t h e mapping routine is t h e drawing of a b o r d e r around t h e map. Once t h e map is completed, hitting any function key will put t h e u s e r in t h e s u r f a c e manipulation mode.

Surface Manipulation

When all calculations f o r t h e s u r f a c e have been completed (drawing t h e bord- er is t h e last s t e p in t h e process), t h e u s e r may view labeling and o t h e r pertinent information by, entering GI>. A new s c r e e n will a p p e a r with t h e pertinent infor- mation, and a new s c r e e n manipulaLon menu at t h e bottom.

<F1> View Map

-

This option allows t h e u s e r t o flip back and f o r t h between t h e map and information s c r e e n s with the touch of a key.

<FZ> Add Grid

-

This option enables t h e u s e r t o add a grid t o t h e s c r e e n map in o r d e r t o g e t more p r e c i s e z and y a x i s readings. Within this option t h e u s e r may chose where t o start t h e grid on each axis, t h e grid line increments, t h e color of t h e grid lines, and also a color t o "exclude" from t h e grid. W e have found t h a t i t i s sometimes more informative t o leave t h e contour lines intact, on t o p of t h e grid, because i t r e l e g a t e s t h e grid t o t h e background, r a t h e r than t o t h e foreground of t h e map. By entering < r e t u r n > f o r each option, t h e default numbers listed on t h e s c r e e n will automatically b e chosen.

->

Save Screen Map

-

This option allows t h e u s e r t o save t h e s c r e e n image on t h e output diskette f o r l a t e r viewing with t h e Recall procedure included in t h e Main Menu.

U;rq> View Key

-

This option will put t h e color key of specified size on t h e s c r e e n f o r viewing o r printing.

->

R e t u r n to Main Menu

-

This option ends t h e map manipulation pro- cedure, and puts t h e u s e r back at t h e main menu level.

D: Recall screen file

A s mentioned in t h e previous section, i t is possible t o save a map with t h e G 3 > command, and then r e c a l l i t from a diskette with this command. After t h e file name and disk drive is e n t e r e d , t h e file will a p p e a r on t h e s c r e e n , and all map manipulation options mentioned in t h e previous section will again b e possible.

E: Return to DOS

Selecting this option will end t h e LEXIS session and r e t u r n t h e u s e r t o t h e DOS operating system.

ALGORITEIM AND DESIGN DECISIONS

To more fully understand t h e shaded contour maps c r e a t e d - b y t h e LEXIS pro- gram, t h e u s e r may find i t helpful t o understand t h e general n a t u r e of t h e algo- rithm used in LEXIS and t o b e aware of c e r t a i n design decisions t h a t w e made o v e r t h e course of t h e program's development. The program resulted from frequent in- teraction between a demographer with some knowledge of computers and a comput- er science student with a keen i n t e r e s t in demography. Working together t o develop t h e program and simultaneously conducting some substantive r e s e a r c h with i t enabled u s t o make substantial improvements in t h e program in i t s eighteen months of development. This section outlines some of t h e more subtle f e a t u r e s of t h e shaded contour maps c r e a t e d by t h e program.

I t is important t o f i r s t discuss t h e differences t h a t exist between t h e LEXIS contour maps and t h e more conventional contour maps often used by geographers, a r c h i t e c t s , geologists, and o t h e r s interested in studying surfaces. The most obvi- ous difference is t h a t w e have chosen t o shade t h e LEXIS maps t o show t h e various levels of t h e surface, r a t h e r than t o label t h e lines with numbers. This procedure allows us t o indicate "cliffs" on a s u r f a c e without drawing multiple contour lines closely spaced together. That is, sudden s u r f a c e changes of more than one level a r e r e p r e s e n t e d by a single contour line, with t h e rapid change in level indicated by a jump in color o r shade between t h e adjacent regions.

Because t h e LEXIS program does no interpolation before creating a surface, t h e appearance of a contour map depends on t h e number of d a t a points used in creating it. Maps c r e a t e d with few d a t a points will tend t o include strong rectangu- lar p a t t e r n s , whereas contours on maps made from l a r g e r a r r a y s of d a t a will ap- p e a r more rounded. I t is possible t o change t h e a p p e a r a n c e of t h e maps with a lit- t l e creativity. Rounded maps will become more rectangular if enlarged and viewed in portions. Rectangular contours can b e smoothed by interpolating t h e d a t a t o produce a l a r g e r a r r a y of d a t a points.

The LEXIS program determines t h e location of contour lines by replacing ac- tual d a t a points with integers representing t h e t i e r , o r region of height, into which t h e d a t a point falls. With fifteen contour lines. t h e r e a r e sixteen t i e r s on t h e sur- face. Next, each point is evaluated in terms of i t s relationship t o adjacent points.

Various p a t t e r n s among nine-point squares are included in t h e program, and each point, with t h e eight points t h a t surround i t , is checked f o r conformity with one of t h e s e patterns. If t h e actual p a t t e r n is s o complex t h a t t h e r e is more than one discontinuity, t h e middle point is surrounded by a box. W e chose this simple

method of drawing lines to b e a reasonable compromise between t h e competing goals of minimizing computational time and maximizing t h e smoothness and a c c u r a c y of contour lines.

Each d a t a point in a n a r r a y i s assumed by t h e LEXIS program t o r e p r e s e n t t h e height of t h e s u r f a c e in a box surrounding t h e point. F o r d a t a pertaining to single y e a r s of time and a g e , e a c h box i s one y e a r by o n e y e a r . The tick marks placed along t h e edges of t h e map c o r r e s p o n d to t h e mid-points of t h e boxes t h a t t h e y d e s c r i b e . Thus, a tick mark at a g e z e r o , say, will a p p e a r o f f s e t slightly from t h e origin and a tick mark at y e a r 1980, in a map t h a t r u n s t h r o u g h 1980, will a p p e a r slightly b e f o r e t h e end of t h e horizontal axis.

If you have any questions or suggestions concerning LEXIS, please write t o one of u s at t h e a d d r e s s e s given at t h e beginning of t h i s p a p e r .

APPENDIX

Example D a t a Map

In o r d e r to alleviate t h e f r u s t r a t i o n t h a t often r e s u l t s from using a n unfami- l i a r computer p r o g r a m , t h i s appendix will outline t h e p r o c e d u r e f o r c r e a t i n g a LEXIS map of t h e U.S. f e r t i l i t y d a t a contained on t h e LEXIS distribution diskette.

W e will, however, only include n e c e s s a r y s t e p s , and l e a v e some of t h e m o s t useful options f o r u s e r s to discover for themselves.

S t e p 1: B e g i n n i n g t h e LEWS p r o g r a m

Before beginning t h e p r o c e d u r e , create a work d i s k e t t e by copying a l l of t h e files contained on t h e distribution d i s k e t t e to a d i s k e t t e formatted by your machine. P u t t h i s d i s k e t t e into d r i v e a: ( t h e l e f t side d i s k e t t e drive).

S t e p 2: FtLe I n i t i a L i z a t i o n

The d a t a contained o n t h e d i s k e t t e is U.S. f e r t i l i t y rates (Heuser, 1984) and r u n s from a g e of mother 1 4 to 49 and y e a r 1945 to 1980. To initialize t h i s d a t a , e n t e r A from t h e main menu. Information should b e e n t e r e d as follows:

F i l e I n i t i a l i z a t i o n

---

I n p u t F'i l e N a m e : USFERT

D i s k D r i v e : A: O u t p u t F i l e D i s k D r i v e : A:

F I L E SF'ECIFICATIONS ...

X - A x i s I n f a r m a t i a n

---

S t a r t i n g x : 1945 E n d i n g x : 1980 L a b e l : YEAF:

S t a r t i r ~ g y: I 4 E r i d i n g y : 45) L a b e l :: AGE

S ~ a r c h f o r s u r f a c e I-ligh a n d LC!@ 7 Y

Once this has been completed, e n t e r y to s e a r c h the d a t a set. The y e a r numbers will appear on t h e s c r e e n as the program reads t h e data, beginning with 1945 and ending with 1980. After t h e file has been completely initialized, t h e main menu w i l l reappear.

Step 3: C r e a t i n g t h e M a p

The color pattern is set to t h e s c r e e n patterns by default. s o w e w i l l ignore Main Menu option B and select C to create t h e LEXIS map. The Map Creation menu w i l l now appear on the screen, giving t h e u s e r the option to create a LEXIS map us- ing one o r two input files. Since there is only one data file on t h e diskette, e n t e r A .

The appropriate information should b e entered s o t h a t the s c r e e n looks as follows before continuing:

To input t h e appropriate information, first e n t e r <Fl>. You w i l l prompted t o e n t e r t h e filename t o which you must respond

return >.

and then t h e disk drive of t h e input file. E n t e r t h e appropriate letter h e r e and <return>. You w i l l then be asked if z e r o is in t h e data range. Since U.S. fertility rates could be 0 at Input Fi les: Dr i ve

USFERT--- k

--- -

Zero in Data Range (Y/N)?

y

Specifications:

Start YEAR: 1945

I

_I

End YEAR: 1980

Start AGE 14--

I

End AGE 49--

1

L1: 0.001000 (low)

1

L2: 0.(:)1(:)0(:)(:, 1-3 : . r:) 020000

L4 : (1) , (1) 3 (1) (1) (1) (1)

1

L 5 : 0.c)mc)0c) i 6 : (3

.

070(:)(:)0

L7: 0. 090000

L8: 0.11000(:)

i

1

~ 9 : 0.1~0000 I L10: 0. 150000

\

L11: 0.170000 LIZ: 0.19r:)c)(:,i)

LIZ: 0.210000

I

L14: (:).29(:)0(]0

1

L15: 0.250000 (high)

/

Line Options:

< I > Mortality

<a _{. L . /}

.--.

.. Fertility

~..s.;. Ratio

< 4 > Difference

< 5 > Multiples

( 6 ) Auto-Select

<:7:> Selected

<:a>.

Exit

High:

0.258900 LOW:

0. 0000 1 0

one t h e a g e s and times covered, e n t e r ^y

.

Next, input <F4> t o select t h e appropri- ate contour lines. Since w e are mapping U.S. fertility, e n t e r 2, and then 8 t o re- t u r n t o t h e s c r e e n menu. Since w e want t o view t h e e n t i r e s u r f a c e , t h e r e i s no need t o use t h e <F2> option.

Now, e n t e r <F6> t o start creating t h e map. The p r o c e s s will t a k e about one minute t o complete, and w i l l b e entirely finished when a yellow b o r d e r a p p e a r s around t h e map.

Step 4: Screen ManipuLation a n d e n d i n g

A f t e r t h e e n t i r e map h a s been generated, entering t h e <F1> key will r e v e a l a t e x t s c r e e n with labeling information and t h e s c r e e n manipulation menu. Also, on t h e last line will a p p e a r a s c r e e n manipulation menu which outlines u s e r options at this point in t h e mapping process. In o r d e r to see t h e c o l o r key used in creating t h e map, e n t e r <F4>. After t h e color key a p p e a r s on t h e s c r e e n , hitting <return>

will r e t u r n t h e u s e r t o t h e information s c r e e n . From h e r e , e n t e r <F5> t o end t h e p r o c e s s and r e t u r n t o t h e Main Menu.

Following t h i s example should give t h e u s e r a practical, but superficial, understanding of t h e LEXIS program capabilities. I t i s important t h a t this example b e used only as a supplement to, r a t h e r than substitute f o r , t h e more extensive description contained in t h e f i r s t p a r t of t h e paper.

REFERENCES

Heuser, R.L. (1976) Fertility t a b l e s f o r b i r t h c o h o r t s by color: United S t a t e s , 1917-1973. U .S. Department of H.E. W., Health Resources Administration, Rockville, MD. DHEW Publication No. (HRS) 76-1152.

Vaupel, J.W., B.A. Gambill, and A.I. Yashin (1986) 7'housands of Data a t a GLance:

Shaded C o n t o u r Maps of Demographic S u r f a c e s . Forthcoming Research Re- p o r t . Laxenburg, Austria: International Institute f o r Applied Systems Analysis.