7/25/2019 5001309

1/6

Is Impulse Purchasing Really a Useful

on ept for Marketing Decisions?

DA VID T KOLLAT

a n d

RON ALD P WILLETT

Impulse purchasing is an

important aspect o f custom-

er in-store behavior as dis-

cussed in the previous ar-

ticle. The authors of this

paper ind icate that the con-

ept as presently employ ed

as limited usefulness as a

dec i -

66 TM PU LS E or unplanned purchasing is a familiar term t

I

most business executives and mark eting academicians.^ In

deed, it is common to refer to certa in prod ucts as imp ulse item s

and or to account for certain kinds of behavio r by classifyin

it as impulse purchasing.

Unplanned purchasing is, of course, not confined to any produc

or reta il settin g. The phenomenon has been used to describe pur

chases of such products as durable goods,- jewelry, wearing ap

parel, hardware items, furniture,^ drugs and toiletries^ and grocer

pro du cts. ' Moreover, the behavior has been found to occur i

such retail settings as drugstores, superm arkets, ' departmen

store s, and variety and specialty stores inclu ding gift shops, flor

ists,

book, barb er, hardw are, auto supply, lumber and furn itur

stores.**

While the above studies indicate that unplanned purchasing oc

curs in many types of retail outlets, it is most commonly studie

in super ma rkets. The importance of this type of behavior in thi

retail settin g is documented by the latest du Pont study, whic

indicates that unplanned purchasing accounts for 50rc of the prod

ucts purchased in food supermarkets.

Several kinds of retailers, particularly supermarket executive

and managers, allegedly use unplanned purchasing as a criterio

for decisions about merchandise location, space allocation and dif

1 As used in this paper, impulse and unplan ned are synonymous.

-

George Katona and Eva Mueller, A Study of Purcha se D ecisions

in Lincoln Clark, editor.

The Dynamics of Consumer Reactions

(New

Yo rk: New York U niversity Pres s. 1955), pp. 30-88.

Vernon T. Clover, Relative Im portanc e of Impulse Buy ing in Reta

S to re s, JOURNAL OF MARKETING, Vol. 25 (J u ly , 1 95 0) , pp . 66-70.

* Drugstore Brand Sw itching and Impulse Buying

(New York: Poi

of Purchase Advertising Insti tute, 1963).

Consumer Buying Habits Studies

(E . I. du Pont de Nem ours and C

1945, 1949, 1954, 1959, 19 65 ); C. Joh n W est. Re sult s of Two Y ea

of Study into Impulse Buying. JOURNAL OF MARKETING, V'ol.

(Ja nu ary . 1951). pp. 362-363; Haw kins Stern, The Significance o

Impulse Buying Today,

JOURNAL OF MARKETING.

Vol. 26 (Apr

1962),

pp. 59-62; and Jam es D. Schaffer, Th e Influence of Impul

Buying or In-the-Store Decisions on Consumer Food Purchase

(Jou rnal pap er no. 2591 from the Michigan Agric ultu ral Exp er

mental Stat ion) .

Same reference as footnote 4, p. 19.

Consumer Buying Habits Studies

(E . I. du Pont de Nem ours and C

1965),

pp. 3-4.

Same reference as footnote 3, p. 67.

7/25/2019 5001309

2/6

80

Journal of Marketing, January, 196

feren tial promotion trea tm ent of items. Certain

store layouts, product locations, shelf locations, and

types of displays are apparently thought to be more

conducive to and consistent with unplanned pur-

chasing than are others. Unplanned purch asing is

also of interest to m anu factu rers. Packaging and

point-of-purchase decisions allegedly are based, in

part, on a product's present or potential rate of

unplanned purchasing.'"

Thus,

the importance and relevance of unplanned

purchasing is apparently widely recognized and ac-

cepted. However, is the concept really a useful

basis for the types of marketing decisions that have

been mentioned above? Th is article discusses four

basic problems with unplanned purchasing that

severely limit its usefulness for marketing decisions.

First, the concept is too vague and encompasses too

many types of behavior to be an operational criterion

for marketing decisions. Second measured un-

planned purchasing rates may be exaggerated be-

cause of the methodology used to generate them,

and may distort the potential for increasing prod-

ucts' sales by manipulation of in-store location and

display. Third present measures of unplanned pur-

chasing rates are misleading bases for selecting

products for differential promotional treatments.

Fourth, unplanned purchase rates for individual

brands may differ significantly from the parent

product category rate, thereby deceiving both re-

tailers and manufacturers .

The Problems of Definition

Since unplanned purchasing is a widely recognized

and frequently talked about type of behavior, it

would seem logical to expect some consensus about

the mean ing of the phenomenon. Actually, this is

not the case, for the term is used in many different

ways. The following are illustrative of the variety

of conceptual definitions:

(1) An impulse purchase is an unplanned, spur

of the moment decision to purchase a prod-

2) An impulse purchase is a logical and effi-

cient way of making purchase decisions, since

by waiting until one is in the store to final-

ize purchase intentions, a more comprehen-

sive and realistic evaluation of purchase

alternatives can often be made.i-

1" Bert C. McCammon, Jr ., "The Role of Point-of-P ur-

chase Display in the Manufacturer's Marketing Mix,"

in Taylor Meloan and Charles Whitlo (editors).

Com-

petition in Marketing (Los Angeles: Graduate School

of Business, University of Southern California, 1964),

p.

78.

William R. Davidson and Alton F. Doody,R etailing

(3) There is no such thing as an impulse pu

chase. Rather, the re are four types of u

planned purchases: (1) Pure impulse is

novelty or escape purchase which breaks

normal buying pattern,

2) Reminder impul

occurs when a shopper sees an item or r

calls an advertisement or other informatio

and remembers that the stock at home is lo

or exhausted, (3) Suggestion impulse pu

chasing occurs when a shopper sees a pro

uct for the first time and visualizes a ne

for it, and (4) Planned impulse purchasi

takes place when the shopper makes specif

purchase decisions on the basis of price sp

cials, coupon offers, and the like.'^

Field studies of unplanned purchasing have e

ployed still other operation al definitions. Th e f

lowing are illustrative:

(4) Shoppers are questioned upon entering t

store as to what they plan to purchase a

records are made of what they do in fact pu

chase. Those items purchased but not me

tioned during the first interview are impu

purchases.

(5) Impulse purchasing is the difference in p

chases between a sample of customers

porting actual purchases (exposed to in-sto

stimuli) and another sample of customers

porting what they anticipated buying wh

Hawkins Stern, "The Significance of Impulse Buyi

Today," JOURNAL OF MARKETING. Vol. 26 (Ap

1962), p. 59.

Same reference as footnote 7, p. 2.

ABOUT THE AUTHORS. Dav id T.

KoUort is an Associate Prolessor of Mar-

keting at The Ohio State University. Di.

Kollat has published articles in theJour-

nal ot Marketinq Research the Proceed-

ings of the American Marketing Associ-

ation,

and has been a contributor to the

Ejicyclopaedia Britannica. He is coau-

thor of Consumer Behavior and Cases

in Consumer Behavior

and is als o a co-

author of a forthcoming book Research

in Consumer Behavior.

Ronald P. Willett is Associate Profes-

sor of Marketing and Assistant Chair-

man. Marketing Department, Indiana

University. He holds BS and MBA de-

gr ee s from Miami Univ ersity Oxford)

and his DBA is from Indiana University.

Dr.

Willett is currently Director of the

Pharmacists Buying Behavior Study and

7/25/2019 5001309

3/6

Is Impulse Purchasing Really a Useful Concept for Marketing Decisions?

sitting in their living rooms (not exposed to

in-store stimuli) .'^

(6) Impulse purchasing is the difference in a

store's sales volume during weeks in which

a holiday occurred with the week immediately

following during which a holiday did not

occur.'^^

From the above, it appears that there are con-

siderable differences of opinion as to what is meant

by an impulse pur cha se.' Conceptual definitions

diflfer not only in degrees of precision but, more

basically, in terms of the amount and type of deci-

sion making that is involved, and, by implication,

the susceptibility of the behavior to marketer strat-

egies. Sim ilarly, there is considerable var iation in

the way in which impulse purchasing is empirically

efined. Fina lly, and perha ps most imp ortan tly,

there are conspicuous differences between conceptual

and empirical definitions.

The lack of consensus about the meaning of im-

pulse purchasing would seem to limit the usefulness

f the concept. The different definitions used in

empirical studies make it difficult to compare find-

ings and accumulate information about the nature

of the behavior. Moreover, the mark eting implica-

tions of impulse buying sometimes vary according

to which definition is adopted. Fo r example, if

definition (1) is accepted, it may be advantag eous

o periodically relocate products having high un-

lanned purchasing rates in order to increase cus-

omer expo sure. In co ntr ast , if definition

(2)

is

ularly if the location(s) is inconsistent with where

Finally, and perhaps most basic, it is questionable

or what it involves. Th at is, how

Impulse Pureh as ing Fact or A rt i fac t?

There are differences of opinion about why im-

se purc hasin g occurs. Two conflicting explana-

Jam es D. Schaffer, The Influence of Impulse Buying

or In-the-Store Decisions on Consumer Food Pur-

chases (Jou rna l paper no. 2591 from the Michigan

Agricultural Experimental Station).

Same reference as footnote 3. p. 68.

For other definitions of impulse purchasing, seeHow

opl

Shop for Food

(Market Research Corporation

of America, undated manuscript) ; One On The Aisle

The Exposure Hypothesis

According to this hypothesis, exposure to in-store

stimuli produces unplanned purchases because: (1)

shoppers use product assortments and other in-store

stimuli to remind them of their shopping needs;

that is, shoppers make some purchase decisions in

the store rather than relying solely on a shopping

list; and/or (2) in-store promotional techniques

result in shoppers recognizing new ways of satis-

fying needs.

Several studies have indicated that in-store stim-

uli can trig ge r unplanned purchases. For example,

it has been demonstrated that the store location of

such products as bread, milk and dairy products is

instrumental in precipitating unplanned purchases

of surrou ndin g products. * Point-of-purchase dis

plays, signs.^'-' and shelf extenders'- are illustrativ

of other promotional techniques that have, in some

instances, proven effective in stimulating impulse

purchases.

However, increasing product exposure does not

always increase the rate of unplanned purchasing

For example, one study has shown that some prod-

ucts with relatively high impulse purchasing rates

(Tang, hominy, powdered coffee cream) are not more

responsive to increases in shelf spacethan the sales

of products having relatively low impulse purchasing

rates (bakin g so da ).- ' Moreover, in some instances,

end-aisle displays of relatively high impulse prod

ucts (pie crust mix and apple pie filling) do no

produce greater direct product profits than the end-

aisle treatment of relatively low impulse products

(spag hetti and spa ghe tti sauce) .-'-

Thus, contrary to what seems to be the opinion

of many marketing academicians and practitioners

exposure to in-store stimuli triggers only some un

planned purchasing, not all of it. The rat e of un-

planned purchasing appears to depend on the type

of stimulation technique, the product that is being

1* Lawrence W. Patterson, In-Store Traffic Flow (Ne

York: Point-of-Purchase Advertising, Institute, Inc.

1963),

p. 2.

'^ See, for example. ^4

First Study of Totality o f Impac

of Point-of-Purchase Material on Plus Sales in Super

markets

( N e w

Y or k : Po in t - o f - Pur c ha se A dve r t i s i n

I ns t i t u t e , I nc . ,1959) , p . 18 ;

Drugstore Brand Siritch

ing an d Impulse Buying ( N e w Y or k : Po in t - o f - Pu

chase Adver t i s ing Ins t i tute , I nc . ,1963) , p . 10 ;

Pac

age Store Brand Sw-itching an d Impulse Buying

( N e w

Y or k : Po in t - o f - Pur c ha se A dve r t i s i ng I ns t i t u t e , 1963)

p.

10.

-* Sa mu el Ro uda ,

W hat Today's Supermarket Chain

Expect from Manufacturers

in

Promotional Suppo

( N e w Y or k : Po in t - o f - Pur c ha se A dve r t i s i ng I ns t i t u t e

1 9 5 7 ) , p . 64 .

21 K eith

C o x , T h e

Re spons ive ne ss

of

Food Sales

t

Shelf Space Changes in S u p e r m a r k e t s ,

Joumal o

Marketing Research, V o l . 1 ( M ay ,1964) , p p . 63-6

7/25/2019 5001309

4/6

8

Journal of Marketing January 19

promoted, and the customer who selectively exposes

himself to, and selectively perceives, the promotional

stim uli. If in-store stimuli do not precip itate all

unplanned purchasing, then it follows that other

factors must be causing some of this type of

behavior.

The Custonter-commitment Hypothesis

The customer-commitment hypothesis maintains

unplanned purchasing, or differences between pur-

chase intentions and actual purchases, are attribut-

able, in part, to incomplete measures of purchase

plaris.

Measured purchase intention s are not the

same as actual purchase inten tion s because the

shopper is iinicilling and/or unable to commit the

time and/or cognitive resources necessary to make

the two types of purchase intentions equivalent.

The customer may be

ununlling

to itemize her

purchase intentions because she does not want to

invest the amount of time and thought necessary

to give the interviewer a complete roster of her

purchase plans. Instead, she artic ula tes only an

incomplete itemization of what she plans to purchase,

thereby satisfying the requirements of the interview

without spending too much time or having to think

too much.

There are several reasons why the shopper may be

unable to itemize her purch ase plans. Fir st, the

shopper may know what she will purchase but may

be unable to articulate these purchase intentions

because of the characteristics of the interview.

The methodology used in most .studies of unplanned

purchasing forces the shopper, in the absence of a

shopping list, to rely on memory for purchase in-

tentio ns. In other words, unaided and nearly spon-

taneous recall is usually used to measure purchase

plans. Thus the methodology alone guarantees that

measured purchase plans will deviate to some degree

from actual purchase plans.

Second, the shopper may know what she will pur-

chase but may be unable to relate these intentions

regardless of the amount of assistance given by the

interview er. Tha t is. with out exposure to in-store

stimuli, the shopper may be unable to construct

cognitively and verbalize for the interviewer what

she will purchase.

The logic underlying the customer-commitment

hypothesis was alluded to nearly two decades ago.-'-^

The hypothesis was also deduced from a recent study

of the unplanned purchasing behavior of 600 super-

m ark et shoppers.-' Since the hyp othe sis was a by-

product rather than an objective of the study, it

was not pos.sible to determine the amount of un-

3

William A pplebaum, Stud ying Customer Behavior

in Retail Stores, JOURNAL OF MARKETING. Vol. 16

planned purchasing caused by the phenomena co

prising the hypothesis.

Implications

To the extent that unplanned purchasing is

tributable to the customer-commitment hypothes

unplanned purchasing is not unplanned at all, b

rather an artifact of the way in which the beh

ior is mea sured. Conseq uently, true unplanned p

chase rates are considerably lower than these th

are currently accepted. Tha t is to say, pre-shoppi

decisions about products and brands to be p

chased are more common than past studies ha

indicated.

The evidence presented indicates that presen

accepted rates of unplanned purchasing-' may

aggerate the potential for influencing buying de

sions.

As a consequence, promotional exp enditu

designed to increase the rate of unplanned purch

ing may be excessive. Conclusions concerning

degree of excessiveness must be postponed until

quantitative impact of the customer-commitment h

pothesis is determined.

Promotional Implications

Retailers sometimes use product unplanned p

chasing rates to select products for differential p

motional tre atm en ts. Such decisions as store lo

tion, shelf height, number of shelf facings, and e

aisle treatment for specific products are often bas

in part, on product unplanned purchase rates.

Since some unplanned purchasing is not unplann

at all, but an artifact of the way in which the

havior is measured, trve unplanned purchas

rates are considerably lower than those that

cur ren tly accepted. It seems risky to assume t

all product unplanned purchasing rates are infla

to the same degree; rather, some product rates

probably overstated more than are others.

Research to date does not facilitate measuring

extent of distortion of unplanned rates across pr

ucts but the direction of bias can be suggest

Based on the customer commitment explanation

bias in unplanned rates is likely to be high for ite

that are discretionary rather than staple, or h

low frequencies of purchase or have highly varia

interpurchase time periods. These same charac

istics are purported to be determinants of unplan

purchase rate s. Hence, product categories with h

measured unplanned purchase rates are also likely

demonstrate greater measurement error, and c

versely, products with low unplanned purchase r

exhib it smaller am ounts of err or . As a conseque

there may be a smaller range between prod

purported to have high and low unplanned purch

rates, and the use of these rates as a single crite

for assignment of promotional effort may be q

7/25/2019 5001309

5/6

Is Impulse Purchasing Realty a Useful Concept for Marketing Decisions?

83

Thus, although direct empirical evidence is not

available, from the evidence presented above it ap-

pears legitimate to deduce that existing unplanned

purchase rates are likely to be misleading bases for

selecting products for promotional efforts.

Product Category Rates May Be Misleading

Unplanned purchasing rates are typically reported

by product category.-* It is often dangerous to as-

sume that a specific brand's unplanned purchasing

rate is equal to the product category average.

In one instance studied, for example, a food prod-

uct category had an average unplanned purchase

rate of

b\^c.

Although most of the brands in this

category had unplanned rates approximating

bl ^ c,

the unplanned rate for one major brand was only

26 27

For reasons already mentioned, the above figures

may not represent the

true

unplanned rates. How-

ever, for purposes of discussion, assume that they

are correct. If so. then the product category rate

may be misleading to both retailers and manu-

facturers.

If retailers fail to recognize that the unplanned

rates of individu al bra nd s may differ significantly

from the product category rate, then,

all other things

being equal,

they are likely to be indifferent as to

which brand within a product category is given spe-

cial promotional treatm ent . In the above case this

may be a mistake, since sales of the brand having

the lower unplanned rate may be less responsive to

ome special promotional efforts. Th us, basing pro-

otion decisions on product category averages rather

Product category rates may also be misleading to

ufactu rers. In the above case, for example, the

w rate . Does it mean tha t he is doing

Why is he not gettin g a competitive sh are

f in-store purch ase decisions? The point, of course,

Toward an Operational Concept of

Impulse Purchas ing

Unplanned Purchasing Can Become a

From the discussion above it is apparent that sev-

eral problems must be overcome before unplanned

purchasing can become a useful concept for market-

ing decisions.

First,

the concept must be precisely

defined. Since the value of the concept h inge s in

large part on empirical studies of the extent and

nature of the behavior, it seems desirable to adop

a definition used in empirical studies, providing

that it is capable of yielding managerially relevant

insights.

Second

a series of methodological studies

needs to be conducted in order to devise a measuring

instrument and process that will equate measured

and actual purchase intentions. Space limitations

prohibit a detailed presentation of such studies here

In general, however, it would appear useful to de-

termine experimentally the effects of interviewer

cueing and customer incentives on the rate of un-

planned purchasing. Experimental manipulation of

interviewer cueing would attempt to determine the

extent to which inability to itemize purchase inten-

tions artificially create s subsequent unplanned pur-

chas ing. Variou s levels and types of incentives could

be used to overcome customer unwillingness to artic-

ulate purchase intentions.

Finally,

unplanned pur

chasing ra tes need to be computed for individua

brands as well as product categories.

Overcoming these problems will involve a substan-

tial commitment of time and resources. However, the

potential value of

true

rates of unplanned purchas

ing may exceed the costs of obtaining them. When

true

rates are determined, other categories of plan

ningspecifically planned, generally planned, and

brand substitutionwould probably differ, both in

magnitude and in relative occurrence, from those

that are currently accepted. These refined measures

of various types of in-store decisions would provide

more sensitive indices of the amount and type of

promotional effort that should be allocated to

products.

Refined measures of unplanned purchasing would

permit a partial functional analysis of the strength

and weaknesses of a firm's promotional program

For example, if unplanned purchasing were defined

and measured in such a way as to be equivalent to

in-store purchase decisions, a manufacturer could

use rates of unplanned p urchasing for his brand (si

as a criterion for evaluating the effectiveness of both

his advertising and in-store promotional strategy

Pure

measures of unplanned purchasing and othe

categories of planning would constitute one of th

most potentially meaningful indices of the real effect

of specific in-store product promotions. For example

the difference in a product's unplanned purchase rat

before and after a special in-store promotion could

be used by the retailer as a measure of the effective

ness of that strategy. Other planning categorie

could also be used in this manner. These m easure

of effectiveness seem particularly useful since the

7/25/2019 5001309

6/6