The Study of a Service Area

Mary Wegner

Mary Wegner is a Geography student at Valparaiso Un iversity. She has been active in her local G TU chapter.

Valparaiso, with a population of 20,900 as of 1970, is a city which serves the inhabitants of Porter County in northwest Indiana. The exact variety and combination of its services are not duplicated anywhere else in the world . In addition to the expected municipal functions for a city of its size (e.g. street repair, police and fire protection , mail and newspaper deliveries, shopping, and recreation facilities), Valparaiso also performs functions that other towns in the immediate vicinity do not provide. Examples of such functions include serving as the county seat of Porter County; housing the only Lutheran university in the Midwest; and providing hospital care through the only hospital in Porter County.

To define the service area or sphere of influence of a central place, it is essential to study individually those services that contribute substantially to the economic base of that place. When the boundaries of several service areas for a specific town are superimposed, a general picture of the entire area of dominance should emerge. This study is a partial attempt to discover the extent of Valparaiso's influence. The service chosen for consideration was health care, with particular emphasis on Porter Memorial Hospital. The major goal of researching this special function of Valparaiso was to determine the size and intensity of the health care service area as reflected through Porter Memorial Hospital.

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Hypothesis and Organization of the Study

The hypothesis which served as the framework for this study was, "The service area of Porter Memorial Hospital decreases in intensity with increasing distance from Valparaiso." Service area, intensity and distance were defined as follows: A service area is that region which surrounds a point (Porter Memorial Hospital) from which a good or service (medical care) is distributed. A decrease in intensity within the service area was defined by a comparison of ratios indicating the number of inhabitants for every one inpatient and outpatient who lived within Valparaiso as compared to ratios calculated for communities surrounding Valparaiso. Distance is a linear measurement on a map, starting from Valparaiso.

The time period covered in the research ran from September 1975 through August 1976. It was felt that this span of twelve months, closest to the start of data collecting, would reflect the most recent trends in hospital usage and would include all seasons of the year. Sources of information were the Emergency Room logbook at Porter Memorial Hospital, and the dismissal notices in the "Hospital Notes" column of Valparaiso's Vidette Messenger. Data gathered from these sources included only town names and how frequently each town appeared as a place of residence for an inpatient or outpatient.

Studies of inpatient residences have been conducted by Porter Memorial Hospital within the last seven years. From 1970 to 1976 investigations of admissions by

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residence were held in the even numbered years during the month of April, with the exception of a study in 1971, also in April. The results of the most recent investigation (April, 1976) were printed in the June 1976 issue of the hospital's Porter's People Paper. The overall indication of the 1976 study was that the hospital handles approximately as many inpatients now as it did in 1974 and 1972. This perhaps pOints to the capacity use of hospital facilities in recent years and possibly indicates that more people could be served if more rooms were available.

The research described in this paper expanded the hospital ' s investigation to include residences of outpatients, and a larger sample of inpatients.

Data were collected for inpatients from every day of the twelve-month period. For reasons of accessibility, collection of information on inpatients differed from the hospital's procedure in that dismissals by residence were used rather than admissions by residence. After keeping daily running tables of towns listed in the dismissal notices of the Vidette Messenger, monthly totals of inpatients were tabulated for each town to reach a yearly total for all places mentioned. These yearly totals were then divided into the respective 1970 census population figures for each town to derive intensity ratios in the form of numbers of inhabitants per inpatient. The ratios were then plotted on a map of northern Indiana by their appropriate cities. Isolines could then be drawn at intervals of five to depict the degree and range of intensity, and

TABLE I

A summary of Data on Inpatients, Sept. 1975 - Aug. 1976

Number of Inhabitantsl City Population Inpatients Inpatient

Beverly Shores 946 8 118.2 Boone Grove 140 8 17.5 Chesterton 6,177 1,440 4.3 Crown Point 13,420 189 71.0 Demotte 1,697 503 3.4 East Gary 15,218 511 29.8 Fair Oaks 200 19 10.5 Grovertown 115 5 23.0 Hamlet 761 7 108.7 Hanna 500 22 22.7 Hebron 1,624 444 3.7 Hobart 22,900 · 696 32.9 Kingsford Heights 1,200 10 120.0 Knox 3,519 49 71 .8 Kouts 1,388 335 4.1 La Crosse 696 100 7.0 Lake Village 400 24 16.7 Leroy 350 12 29.2 Lowel l 3,839 89 43.1 Medaryville 732 12 61 .0 Merri Ilvi lie 26,500 · 218 121 .6 North Judson 1,738 95 18.3 Portage 21 ,200· 2,171 9.8 Porter 3,058 133 23.0 Rensselaer 4,688 39 120.2 Roselawn 150 4 37.5 San Pierre 250 31 8.1 Schneider 426 7 60.9 Shelby 500 24 20.8 Tefft 125 13 9.6 Thayer 300 16 18.7 Union Mi lls 400 11 36.4 Valparaiso 20,900 · 5,293 3.9 Wanatah 773 200 3.9 Westvil le 2,614 155 16.9 Wheatf ield 713 240 3.0 Wheeler 400 53 7.5

14,084

· These populat ion f igures are 1975 est imates as found in the 1975 Commercial Atlas and Marketing Guide, 106th edition, Rand McNally Company, 1975. All other populat ion f igures are from the 1970 census.

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Fi g u re

Inhabitants/Inpatient

L a k e

1

I 1

I I

I ~ .~

.."

S tAL E

D I,

10

M i chigan

15 Mi. I

• Rensselaer 120

LEGEND

61ntustJh H"hwJY

o U. S. Hilhway

o SI&lt. HiC h ""

Knot 11.8

• Citlu put i n rnt to Ihe study

D .County seals

Excepllons to I he --' pattern

Soulh Bend 9 Mi .

to show the general size and shape of the inpatient service area.

The data collection procedure was very similar for outpatients. In view of the large number of outpatients handled by the hospital (over 24,000 per year) it was decided to limit the collection of outpatient data to 60 days out of the year. Five days from each month were selected via a table of random numbers. Again, running accounts were kept listing each town discovered in the Emergency Room logbook. After figuring the yearly outpatient totals for each town, ratios of numbers of inhabitants per outpatient were calculated . These, too, were plotted on a map and isolines drawn at intervals of ten to visually represent the outpatient data and service area.

Presentation and Analysis of Data

A summary of inpatient data is found in Table I. Every name listed in the "Hospital Notes" under dismissal notices in the Vidette Messenger was included in the totals except newborn babies dismissed with their mothers. These children would not have been reflected in the 1970 population figures that were used in the ratio calculations and were not counted for that reason.

It should be noted that not all dismissed patients' names may have appeared in the paper since a patient may request that their name be withheld from the list. The dismissal notices list patients by Post Office addresses only and do not indicate rural route residency. Therefore the possibility exists that a number of people may have been counted in the final patient totals who actually lived outside the town

in which they were listed as residing .

There were over one hundred out of state inpatients listed, over half of which came from Michigan and Illinois. Within Indiana, approximately four hundred patients were classified as being inhabitants of the state of Indiana, but were from places too distant to be a part of the basic inpatient service area.

From Figure I it can be seen that the intensity of inpatients served by Porter Memorial Hospital does decrease with increasing distance from Valparaiso. The isolines show that after certain distances (depending on the direction from Valparaiso) the intensity decreases at an increasing rate . This noticeable drop in intensity follows a line from Chesterton clockwise to Westville, Hanna, North Judson, San Pierre, Fair Oaks, Thayer, Hebron, Wheeler, and Portage. Exceptions to the pattern are Lake Village on Highway 41 and Grovertown on Highway 30 east of Valparaiso. These are small towns with populations of 400 and 115 respectively. There does not seem to be a logical explanation for these exceptions, especially since the towns nearby have similar sized populations, and fewer people on the inpatient list for the time period in study.

Outpatient data are summarized in Table II. An omission occurs with this data in that the Emergency Room logbooks listed over 1,000 outpatients with a rural route address that were not included in the collected data. They were excluded because urban population figures were used to calculate the intensity ratios. It would have been difficult to pinpoint the locations of

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these addresses for purposes of illustration. Out of a total of thirty­four "outpatient" towns, thirty-one referred to people who lived on rural routes. Nine out of these thirty-one had more than twenty-five rural inhabitants for the sixty days studied: Chesterton, Demotte, Hebron, Hobart, Kouts, Valparaiso, Wanatah, Westville and Wheatfield.

Out of state outpatients numbered over one hundred, again over half were from Michigan and Illinois. For both inpatients and outpatients, Ohio, Pennsylvania and Wisconsin had the next highest representations. This trend appears to reflect accidents involved in the east-west traffic flow running through northwest Indiana.

TABLE II

A Summary of Data on Outpatients, Sept. 1975 - Aug. 1976

City

Beverly Shores Boone Grove Chesterton Crown Point Demotte Dune Acres East Gary Fair Oaks Hanna Hebron Hobart Kingsford Heights Kouts La Crosse Lake Village Lowell Medaryville Merrillville North Judson Ogden Dunes Portage Porter Roselawn San Pierre Schneider Shelby Tefft Thayer Union Mills Valparaiso Wanatah Westville Wheatfield Wheeler

-1975 population estimate.

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Population

946 140

6,177 13,420 1,697

301 15,218

200 500

1,624 22,900-1,200 1,388

696 400

3,839 732

26,500-1,738 1,361

21 ,200-3,058

150 250 426 500 125 300 400

20,900-773

2,614 713 400

Number of Outpatients

7 17

407 38 38

1 154

2 6

48 126

4 69 10

5 14

2 40 9

19 846

53 1 6 2 5 6 2

10 2,174

50 66 24 24

4,285

Inhabltantsl Outpatient

135.1 8.2

15.2 358.2

44.7 301 .0 98.8

100.0 83.3 33.8

181.7 300.0

20.1 69.6 80.0

274.2 266.0 662.5 193.1

71 .6 25.1 57.7

150.0 41.7

213.0 100.0 20.8

150.0 40.0 9.6

15.5 39.6 29.7 16.7

Fig u re II

In habi I anI s/Oulpal i en I

L a k t M ichi gan

o I I

L.k. , Vill'I'1 ~/

seA L (

1,0 15 Mi. I

D Rensulur

LEGEND

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o u.s. Hia h •• , o StaJo Hiah •• ,

Knol

• Citiu putine"t I, t he: study

a .c.unt, Jilts

.. ., hC~;ltlons to thl pattt,n.

South Brnd 9 MI.

Grover -

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Approximately two hundred outpatients were in the category of living within Indiana but were once more too distant to be included in the basic outpatient service area.

From Figure II it can be seen that the intensity of outpatients served decreases with increasing distance from Valparaiso. The area which is bounded by the sharp drop in service illustrated by the closely spaced isolines, runs clockwise from Chesterton to Union Mills, Tefft , Demotte, Wheeler, and Portage. The exceptions which do not follow the regular isoline pattern in Figure II, are Dune Acres, Hobart and Lake Village. These exceptions may be due to sampling errors. In addition, Hobart is one of the largest towns from which data were collected, and would most likely have its own family doctors or clinics to handle outpatients. Dune Acres and Lake Village are smaller communities that would be more subject to chance findings than a larger town with a population of sufficient size to provide a continuous flow of outpatients into Valparaiso.

If the maps of both types of services researched in this paper are combined , the basic service area of Porter Memorial Hospital is bordered by Portage and Chesterton to the north, Westville south to San Pierre on the east, San Pierre and Demotte to the south, and Demotte north to Wheeler on the west, an area which covers more than 375 square miles. The service area stretches farthest to the south of Valparaiso on both maps, partly due to Lake Michigan as a boundary, but also due to the influence of hospital facilities in cities larger than Valparaiso such as LaPorte and South Bend to the

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northeast, and Gary and Chicago to the northwest. The presence of the major east-west highways in the service area to the north, and the presence of a sizable rural and small town population to the south (close to twenty cities studied have populations below 1,000) point to two types of patient care the hospital should continue to develop and expand: Emergency and special-unit care for victims of automobile and farm related accidents.

Conclusions and Summary

The data support the hypothesis as well as provide a means by which to define the boundaries of Porter Memorial Hospital's sphere of influence. The service area, as expected, decreases in intenSity with distance from Valparaiso. Additionally, health care is not only provided to citizens of Valparaiso but to all of Porter County and beyond. Thousands of people have benefitted from the presence of the hospital and will continue to do so in the future. The hospital has expanded its facilities and services several times as the population has increased in the Valparaiso area. With the addition of more hospital space, the hospital will enlarge its vital role of continuing to maintain the good health of the people it serves. Porter Memorial Hospital , as viewed from the results of this research, will remain a growing, necessary asset to the economic base of Valparaiso. Any expansion of its service area is likely to occur in a southerly direction. Such expansion would undoubtedly reflect the acquisition of expensive, highly specialized equipment not available at smaller health care of hospital centers.