Targeted Consumer Information and Prices: The Private and Social Gains

to Matching Consumers with Products 

David Reiffen

Federal Trade Commission

April, 2001

Abstract

It is well known that product differentiation increases both prices and profits, other things

equal. What is less well understood is how the distribution of consumer preferences affects firms’

incentives to differentiate their products. This paper focuses on the incentive of firms to reveal

truthful information about product attributes. Because consumers’ preferences differ, the revelation

of this information differentiates products. The profitability of inducing this differentiation is shown

to be related to three aspects of the information; the size of the “targeted” group (i.e., the group who

finds these attributes desirable), the magnitude of the perceived change in attributes induced by the

information, and whether the information is “symmetric.” In particular, I show that the profits

associated with information increase more than proportionately with the size of the targeted group.

This implies that information will tend to be provided for large groups, even if there are no

economies of scale in producing that information. The analysis also shows that in some

circumstances, the revelation of asymmetric information can actually reduce the firm’s profit. 

The views expressed here are those of the author alone, and do not reflect those of the Federal Trade

Commission, nor any Commissioner. I would like to thank Cindy Alexander, Jeremy Bulow, Dan

Hosken, Chuck Thomas and John Yun for helpful discussions of this paper, and Sara Harkavy for

excellent assistance with its preparation.
1

In contrast, Grossman and Shapiro (1984) show that information about the existence and

prices of rival goods results in greater substitutability between products, and lower prices.

1

I. Introduction

Is one better off being part of a small group, or a large one? In some contexts, there are clear

advantages to being part of a small group. For example, it has been estimated that wages for

individuals in smaller age cohorts earn more when entering the job market than those in larger

cohorts (see, e.g., Welch, 1979). In other circumstances, there are advantages to being part of a

large group. Some cases in which being part of a large group is advantageous include the outcome

of voting and the purchase of products for which there is significant R&D required to create the

product, such as pharmaceuticals and automobiles. With the graying of the baby boom generation,

it is not surprising that products such as the prescription hair loss treatment Propecia and night-vision

windshields for automobiles have reached the market.

 In these two examples, the existence of a large market for a product appears to justify the

high R&D expenses undertaken by the producer. This paper highlights a second, perhaps subtler

advantage to being a member of a large group. Suppose a producer can develop information that

shows his brand of a product works well for a specific “targeted” subset of the population (e.g., the

effectiveness of his drug for a specific age group), but poorly for another group. Such “matching”

information may not increase his unit sales, but can be profitable because it differentiates his brand,

leading to higher prices.1

Previous work, such as Anderson and Renault (A&R, 2000) and Meurer and Stahl (M&S,

1994), has shown that information of this type can increase prices. Because information revelation

leads to higher prices, which induce a transfer from consumers to producers, information may be
2Whether it is appropriate to think of exogenous groups as existing in the population

depends on the context. For pharmaceuticals, it seems appropriate to think of exogenouslydetermined groups (e.g., adult males) with a common “quality” parameter.

2

privately profitable, but reduce welfare. M&S find that firms have an excess incentive to inform

consumers of their product’s characteristics, because firms’ profits from providing information

reflect gains due to both superior matches between consumers and products, and to the transfer from

inframarginal consumers caused by the higher prices. A&R find that consumers overinvest in

information about product characteristics because they ignore the transfer from other consumers to

producers caused by the information. Hence, in both of these models, the private gain to information

exceeds the social gain, and on the margin, too much information is produced.

This paper takes a somewhat different approach by assuming there are groups within the

population (e.g., specific age groups) with common characteristics, and firms have information about

the match between those characteristics and the features of their products. It analyzes the

relationship between group size and the price effects of information.2 Specifically, it shows that the

marginal effect of information on price is increasing in the targeted group’s size. It follows that even

if the costs of gathering and revealing the information are proportional to the size of the group, the

profitability of gathering and revealing the information will be increasing in group size, and hence

information revelation may be profitable only for large targeted groups. In fact, this paper shows that

the incentive to produce information may be less than socially optimal, especially for small groups.

These results might explain some apparent biases in drug research. It is often claimed that

certain smaller groups of patients with a given ailment are underrepresented in clinical trials (e.g.,

female cardiac patients). Of course, one reason that male cardiac patients might receive more

clinical attention is that there are economies of scale in clinical research (e.g., the size of the sample
3

In section V, I discuss the alternative interpretation that the information about the

efficacy of drug for one group has no effect on the expected efficacy by patients in other groups.

3

group required for obtaining FDA approval to list an additional indication or patient population for

a drug is independent of the size of the user population). However, a second reason is suggested

by this analysis; information about the suitability of a drug for male patients has a more-thanproportionally larger effect on price than information about female patients.

Explicitly modeling the role of group size permits analysis of another issue relating to the

profitability of information revelation. An assumption made in the previous literature is that

information is symmetric; that is, when information revelation increases the willingness to pay for

a group who learn the brand is well-suited to them, there is another group of the same size whose

willingness to pay falls. There are, however, circumstances in which information can have an

asymmetric effect, whereby the size of the group whose willingness to pay increases is different from

that of the group for whom it falls as a result. For example, suppose clinical trials have revealed that

drugs A and B are equally effective in treating some ailment for the population as a whole. These

clinical trials may conceal important differences in efficacy across groups within the population.

That is, the producer of drug A may know from its clinical studies that its brand has greater efficacy

for some subpopulation (e.g., cardiac patients who are also diabetics), which I refer to as the

“targeted” group. If the average efficacy of the drug is fixed, this means that it is correspondingly

less effective for some or all of the remaining population.3

 It need not be the case that the group for

whom drug A’s effectiveness is lower than average is the same size as the targeted group. For

example, it could be that the subpopulation for whom the drug is more effective than its overall mean

represents 20% of the population, while the drug is less effective than average for the entire
4

remaining 80%.

Whether the information changes the perceived attributes of the product in a symmetric or

asymmetric way has an impact on the price effects of the information, and consequently, on the

profitability of releasing the information. In particular, information that increases a small group’s

willingness to pay for a product and simultaneously reduces it for a large group (holding the average

willingness fixed) can lower the equilibrium profit from selling that product. The reason is that the

firm’s total sales decline because the increased sales from a large increase in willingness to pay for

a small group is less than sales loss from a small decrease in it for a large group. In contrast, if the

group for which willingness to pay falls is the same size (or smaller) than the group for which it

rises, the firm’s profits will rise. 

II. The effect of information on prices

In evaluating the effect of information on prices and output, and the consequent incentive to

disseminate information about product characteristics, I consider a simple duopoly model, along the

lines developed by A&R and M&S. As in those models, information is truthful, and known to be

truthful by all consumers. Consumers buy at most one unit of a product, two differentiated brands

of which are available from two competing sellers. As in the previous work, I normalize the

production costs to zero, although it is costly to inform consumers of each brand’s characteristics.

I depart from this prior work by treating consumers as heterogeneous in two respects; one

aspect that is observable to the sellers, which I refer to as the consumer’s group (e.g., female and

over 65 years of age), and one aspect that is idiosyncratic and unobservable. Specifically, in each

of the K groups, all consumers in that group have a common parameter representing their valuation
4

In the drug example, product corresponds to a class of drugs (e.g., H2 antagonists for

ulcers) and brand corresponds to a specific chemical (e.g., Tagamet or Zantac). Note that

specific differences in the relative efficacy of drugs within a class for different individuals can

sometimes be dramatic. For example, while the two leading anti-herpetics are roughly equally

effective for most patients, only one is approved for use in immuno-compromised (e.g., HIV

positive) individuals. One example of ,ij is consumer j’s valuation of the side effects of drug i. 

In this case, the support of ,ij might be most appropriately thought as (- e

-

, 0). However, the

analysis in the paper can be generalized to negative ,ij with appropriate reinterpretation of the

"i

k

.

5

of brand i (i = A, B) relative to an outside option, and in addition, each consumer has an idiosyncratic

valuation for each product. Hence, for consumer j in group k, the utility from brand i relative to the

outside option (and hence, j’s reservation value) is Uj = "i

k

 - Pi + ,ij , where "i 

k

 is the value of

systematic component of brand i’s “quality” to all consumers in group k, and ,ij is consumer j’s

idiosyncratic valuation of brand i. I assume that ,ij is I.I.D. for the two brands for any group, and

,ij is distributed identically for all groups, with support (0, e

-

) for both brands. For concreteness, one

can think of "i 

k

as the average success rate of drug i in treating an ailment for patients in group k,

multiplied by each consumer’s value of a successful treatment, and ,ij as consumer j’s (unobservable)

idiosyncratic valuation of the drug.4

 Quality is unambiguously defined for each consumer (in that

utility is increasing in "i

, all else equal), but the valuation of the brand varies across consumers

within each group (in this sense, brands are horizontally differentiated). Consumer j (who is a

member of group k) prefers brand A to brand B if "A

k

- PA + ,Aj > "B

k

 - PB + ,Bj. This condition can

usefully be written R = ,Aj - ,Bj > "B

k

- "A

k + PA - PB

. The absence of superscripts on PA and PB

reflects the assumption that firms cannot price discriminate, but instead charge the same price to all

groups. Firm A’s share of sales to

group k is
5This use of the term drastic parallels the use in the R&D literature (see, e.g., Reinganum,

1988). In the R&D literature, drastic refers to a cost reduction due to innovation that is

sufficiently large that the old technology is not a binding constraint on the seller of the

innovation. Analogously, here drastic refers to information that leads to the rival brand no longer

serving as a constraint when selling to the targeted group.

6The condition that f(e

-

) = f(-e

-

) = 0 implies that demand is continuously differentiable.

6

as long as*"B

k

- "A

k

 + PA - PB

* < e

-

. If this inequality does not hold for some k, we refer to "A

k

as a

drastic difference in quality.5 If the quality difference is drastic for some k, then SA

k = 0 or 1,

depending on the sign of "B

k

- "A

k for any particular k. Information will tend to be drastic when

consumer heterogeneity within groups is small relative to differences across groups. Normalizing

the number of consumers to 1, the aggregate demand for A’s product is SA

k

 summed across groups,

where wk is the percentage of the population in group k. The assumptions regarding ,ij imply that

for every group, R has support (-e

-

, e

-

). I also assume that R is symmetrically distributed around 0,

with f(e

-

) = f(-e

-

) = 0, and f’(R) < 0 for R > 0, f’(R) > 0 for R < 0, f’(0) = 0 (i.e., F(R) is unimodal).6

As in A&R and M&S, I assume the two brands are on average, equally attractive. Here, this

means that E wk "A

k

 = E wk "B 

k

 = "^. Returning to the drug example, "^ can be interpreted as the

monetary value of a successful treatment multiplied by the average efficacy of the two drugs in

curing patients with some ailment for the population as a whole. In the absence of information,

consumers in all groups view "^ as the appropriate estimate of this value (that is, "i 

k

 = "^ for all k, i

= A, B). Firms may have the ability to change these estimates of "A

k

 for some groups. In the drug

example, firms may have information from clinical trials that allows them to better match patients

to drugs. For example, the manufacturer of drug A may know that it has a higher success rate among
7

In M&S, ,ij = V for one product, and zero for the other, while the ,ij are I.I.D. in the

A&R model.

8

In section V, I consider a different interpretation of information, where the average

efficacy changes with the information. Specifically, section V considers what happens if "A

k

7

women than among men. In terms of the model, information consists of a set of "A

k

 that can differ

across groups, even though there is still heterogeneity within groups. In contrast, in both the A&R

and M&S models, Uj = ,ij - Pi , and "^ is the expected value of ,ij.

7

 In these models, information

consists of consumers learning their ,ij, and consequently learning which brand better suits them. As

in the previous work, here information about the "A

k

 has effects on prices. Because demand is

continuously differentiable, we can take the derivative of QA with respect to PA which is - E wk f("B

- "A + PA - PB

) < 0 (note that f( ) is zero if the information is drastic for some group), so that firm

A’s first-order condition with respect to its price is

and B’s first-order condition is

These conditions imply that the slopes of the two firms’ best response functions are 

Because the average quality, "^, is assumed fixed, the information that "A

L > "^ implies that

"A

k

 < "^ for one or more other groups.8

 For any given "A

L

 > "^, there are multiple ways that the other
remains equal to "^ for other groups, while "A

1 > "^.

8

"A

k

 can change so that the average quality remains "^. As shown below, how the other "A

k

change

with the information about "A

L will affect the resultant price effect of any given "AL

 > "^. In this

section, I consider “symmetric” changes in the "A

k

. The following section analyzes “asymmetric”

changes.

Definition: A distribution of the "A

k

 is symmetric if whenever "A

L

 > "^ for some group of size wL

then there is some other group of size wM = wL for which "A

M

 is less than "^ by the same amount. 

An implication of a symmetric distribution of the "A

k

 is that "A

M

 + "A

L

 = 2"^. For example,

if group L consists of individuals under 20 years of age (who comprise 30% of the relevant

population) and has "A

L

 > "^, then the distribution of the "A

k

 will be symmetric if the group for which

"A

M

 < "^ also represents 30% of the population, but will be asymmetric if the group for which "A

M

< "^ includes all individuals 20 and over. 

When information is symmetric, a pure strategy symmetric equilibrium in prices can emerge.

Specifically, letting P

S

 = PA

S

 = PB

S

, if 

then, as shown below, there exists a pure strategy symmetric pricing equilibrium. In words,

inequality (6) says that the maximum profit firm A can earn by selling to group L only is less than

its profits at the symmetric equilibrium. Rewriting (6) as 

"A

L

 - "^ - e

-

 < (1-wL)P

S

 /(2 wL) (6'), 

two observations following directly

Observation 1: The left-hand side of (6') is < 0 for non-drastic "A

L

, and > 0 for drastic "A

L

. Hence
9

for any positive P

S

, (6) holds for all non-drastic "A

L

, and some drastic "A

L

.

Observation 2: If MP

S

/M"A

L < (1-w1

)/(2 w1), then (6) will fail to hold for "A

L

 sufficiently large. 

In what follows, I focus on the pure strategy equilibrium that emerges when (6) holds. Note

that when (6) does not hold, then the only equilibria feature mixed strategies. 

Proposition 1: Holding "B

k

 = "^ for all k, an equilibrium exists with PA = PB for symmetric

distributions of the "A

k if condition (6) holds

Proof: Let "A

1> "^ and "A2 < "^ such that "^ - "A2 = "A1

- "^ and w1 = w2. First suppose "A

1

 is not drastic.

This implies that at PA = PB, 

which is equal to 1⁄2 by virtue of the symmetry of f(R). Similarly QB = 1⁄2. Substituting into (2) and

(3) yields 

and 

Because of the symmetry of F(R), f("^B - "A

1

) = f("A

1 

 - "^B) and since w1 = w2, both first-order

conditions are met at the price which solves equation (7) (or equivalently, (8)). 

If the information is drastic, the demand facing retailer A is QA = w1

 + (1-w1 - w2 ) SA

 (as

long as PA < "A

1 

-"^ - e

-

 + PB) while B’s demand is QB = w2 + (1-w1 - w2) SB (assuming PB < - "A

1 +

"^ - e

-

 + PA ). Since w1 = w2, solving equations (2) and (3) yields
10

Note that PA < "A

1 

-"^ - e

-

 + PB and PB < "^ - "A

1 

- e

-

 + PA, at PA

S

 = PB

S

. In addition, as long as w1 ("A

1

-"^ - e

-

) < PA

S

/2, firm A’s profits at PA

S

 exceed the profits that he could earn by selling to group 1

only. Hence, as long as condition (6) is satisfied,P

S

 = 1/[2*(1-2 w1) f(0)] maximizes each firm’s

profits.

Finally, because w1

 f’(R) = - w2

 f’(-R) and f’(R) = 0 for all other groups, whether the

information is drastic or non-drastic, the best response functions have slopes of 1⁄2 at PS, and PA

S

 =

PB

S

 represents an equilibrium. (

This lemma establishes the existence of a symmetric pricing equilibrium for symmetric

distributions of the "A

k

s for which condition (6) holds. The prices in these symmetric equilibria

depend on two parameters; "A

1 

 - "^, and w1, and it useful to write the prices as function of those

parameters; i.e., PA

S ("A

1

, w1). Figure 1 portrays for relationship between PA

S ("A

1

, w1) and "A

1 for

"A

1

 - "^ < 7. As can be seen there, prices are lowest in the absence of information. In the absence

of information, "A

k = "^ for all groups and equations (7) and (8) imply that PAS

 = 1/(2 f(0)). Since

f("A

1

- "^) is less than f(0), this means that the prices are higher than 1/(2 f(0)) whenever there is nondrastic information. Equations (7) - (8) imply that the symmetric equilibrium price is increasing in

"A

1

for non-drastic "A

1

. Comparing equations (7) and (8) with equation (9), we see that in the limit

as "A

1 

- "^ approaches e

-

 (the information approaches being drastic), the prices determined by

equations (7) and (8) approach the price in equation (9). Finally, while equation (9) implies that

prices are higher than 1/(2 f(0)) whenever there is drastic information, it also implies that MP

S

 /M"A

1

= 0; once the information is drastic. Returning to Observations (1) and (2), this last fact implies that
9

Information costs are here modeled as if firm A knew "A

1

 and was calculating the

profitability of publicizing that information. A more realistic interpretation (which is analytically

similar) is that information costs include the manufacturer’s cost of conducting the R&D to

determine "A

1

 (multiplied by the probability he finds "A

1

 > "^) plus the costs of publicizing that

information. 

11

equation (6) will be satisfied for some drastic "A

1

, but it may be profitable for firm A to deviate if

"A

1

 is drastic and sufficiently large.

One way of thinking about the effect of symmetric targeted information is that an increase

in the perceived value of a brand for one group (accompanied by lower value for an identical-sized

group) reduces the impact of a higher price on unit sales (because the density function is lower when

evaluated at higher values of *"A

k

 - "B

k

*), without changing the level of sales. Such a change

increases the profit-maximizing price and the revenues of the firm revealing the information. In the

following section, I show that asymmetric changes in the "A

k

 can have a different effect because they

can influence both the responsiveness of customers to price changes and total sales. For this reason,

the revelation of information about the "A

k

can have ambiguous effects on A’s price and revenues.

One other observation follows directly from equations (7) - (9); prices are increasing in w1

.

Hence, while firm A’s market share is 1⁄2 in all symmetric equilibria, its profits (gross of the cost of

informing consumers) are increasing in the targeted group’s size. In fact, even if it is costly to gather

and disseminate the information and those costs are proportional to group size, the profits from

informing consumers about a given "A

1

 are increasing in the targeted group’s size, as shown below.9

Proposition 2: Assume condition (6) holds and suppose the costs of gathering and disseminating

information are proportional to the size of the group - i.e., information costs are ( w1 (where ( > 0).

If it is profitable to inform a group of size w

~

1

 about a particular "A

1

 > "^ , then 
12

1. it will be profitable to inform a group of size w1 , (w

~

1

, 1⁄2.) (i.e., a larger group) about that "A

1

. 

2. it may be unprofitable to inform a group of size w1 , (0,w

~

1

).

Proof: Suppose there is some w

~

1 , (0, 1⁄2) such that for "A

1

, QA PA

S ("A1 

, w

~

1

) - QA PA

S ("^) - ( w~

1

/2 =

2/2 > 0; that is, at w

~

1

, releasing the information about "A

1 increases revenues by 2/2 more than it

does costs. I wish to demonstrate that for any larger group, *w

~

1 (where * > 1, * w

~

1

 < 1⁄2), releasing

the information is strictly profitable, while releasing the information will be unprofitable for a group

smaller than w

~

1

 for 2 sufficiently small. For a group other than w

~

1

 in size, the change in profits from

releasing the information is QA PA

S

("A

1 

,* w

~

1

) - QA PA

S ("^) - *( w~

1

/2 which is equal to QA PA

S ("A1

,

*w

~

1

) - QA PA

S ("^) - *[ QA

 PA

S ("A

1 

,w

~

1

) - QA PA

S ("^) - 2/2]. To evaluate the sign of this expression, first

consider the case of drastic information. If condition (6) holds, and the information is drastic, then

QA

 = 1⁄2, and QA

 PA

S ("A

1 

,* w

~

1

) - QA

 PA

S ("^A

) - *[QA

 PA

S ("A

1 

,w

~

1

) - QA

 PA

S ("^) - 2/2] equals

since 2* w

~

1< 1, this is positive for * > 1. Hence, releasing the information is strictly profitable for

all w1 , (w

~

1

, 1⁄2). Conversely, expression (10) will be negative for * < 1 and 2 sufficiently small.

Finally, when "A

1 is not drastic, the analogue of expression (10) is 
10For some drugs, there may be some specialization between physicians and patients (i.e.,

pediatricians), so that it may be fairly inexpensive to target the relevant group.

11Perhaps in recognition of this effect, the FDA offers incentives for drug companies to

perform clinical studies on children (who often represent a small share of patients). 

13

Since f(0) + f( "A

1

 - "^ + PA - PB

)+ - 2f( "A

1

 - "^ + PA

 - PB

) > 0, this implies that, as was the case for

drastic information, (10') is positive for * > 1, and negative for * < 1 and 2 sufficiently small. (

The implication of this result is that firms will have (weakly) less incentive to gather

information which benefits small groups, even if the cost of generating and disseminating that

information is proportional to the size of the group, and the average reservation value of the

members of all groups are the same. 

Whether the per-individual costs of informing a group of consumers are increasing or

decreasing in group size depends on the specific context. For prescription drugs, information costs

are likely to increase less than proportionally with group size in most cases. For example, to

establish efficacy for a group, the FDA requires tests whose sample sizes are independent of the size

of the group. In addition, to the extent that informing physicians is the easiest way to disseminate

the information, economies of scale seem likely, since the number of relevant physicians may be

independent of group size.10 This is consistent with the frequently-expressed concern that certain

smaller groups (e.g., female cardiac patients) are underrepresented in clinical studies.11

III. The Effects of Asymmetric Information
12 A third possibility, which is discussed in section V, is that an increase in "A

1

 has no

effect on the other "A

k

, in which case the information increases average quality.

13Of course, information could also be asymmetric if the group whose "A

 fell comprises

less than all of the remaining population. If the group whose "A falls is actually smaller than the

group for whom it rises, the analysis is similar, except that the effects on the two firms are

reversed. That is, similar analysis to Proposition 3 shows that firm A’s sales increase from

revealing the information. 

14

Holding the average quality of a brand of a product fixed, information that reveals a superior

match between that brand and consumers in a specific group necessarily reduces the suitability of

that brand for some or all of the remaining population. In some circumstances, it is plausible that,

contrary to the assumption of symmetry made in the previous section, this reduction in suitability

occurs for a different-sized group than the group that experiences increased suitability.12 As

discussed in an earlier example, information that a drug is particularly suitable to patients under 20

years old could be interpreted as information that it is less suitable for all patients 20 and over. 

This section explores the implications of such asymmetric information on prices and profits.

I assume that the information has a positive effect on the suitability of a brand of a product for a

targeted group representing less than one-half the population. I further assume that the cost of

informing this group are the same whether the information is symmetric or asymmetric. Finally, I

assume that the information has a negative effect on the remaining population that is uniform across

all non-targeted groups.13 That is, firm A’s information is that "A

1

 is greater than "^ and "A

k

 = ("^ -

w1 "A

1

)/(1-w1

) < "^ for all non-targeted groups, with w1

 < 1⁄2 and "A

k

 non-drastic (although "A

1

 may

be drastic). Not surprisingly, such information increases sales to the targeted group, and reduces

sales to the other groups. As Proposition 3 shows, the second effect dominates and total sales fall.
14 Holding "B

k

 = "^ for all k, MP*B(PA)/M"A

1 > 0 if w1

 is less 1⁄2. That is, the information

shifts out B’s best response function. However, the effect on P*A(PB) is ambiguous, so that the

effect of information on prices is ambiguous. In fact, as Figure 5 below demonstrates, it is

possible that information can lower PA.

15

Proposition 3: Suppose "A

1

 > "^A and "A

k

 = ("^A - w1 "A

1

)/(1-w1), with w1 < 1⁄2. Then, evaluated at PA

= PB, A’s sales are decreasing in "A

1

.

Proof: For "A

1

 non-drastic, evaluated at PA = PB, MQA/M"A

1 = w1

[f("^B - "A

1

) - f((w1("A

1

 - "^B)/(1-w1)],

since "A

k

 = "^A

 - w1 "A

1

 /(1-w1

) for k > 1. This is negative for w1 < 1⁄2, since f(R) evaluated at w1

("A

1

-

"^B)/(1-w1) is greater than f(R) evaluated at "A

1

 - "B

1

. For "A

1

drastic, MQA/M"A

1 = w1

[- f(w1("A

1

-

"^B)/(1-w1) + PA

- PB] <0.(

That is, information that "A

1

 is greater than "^ 

that is asymmetric lowers A’s sales, other

things equal. Of course, to determine the effect of the information on A’s profits, one has to

determine the effect on A’s price. Making this determination requires additional structure in the

model.14 Specifically, I assume that the ,ij are distributed uniformly with support (0,1). This implies

F is symmetric with support (-1,1), and f(R) = 1 + R for R < 0, and f(R) = 1 - R for R > 0. 

Under this assumption, the symmetric equilibrium prices with no targeted information are

PA

s ("^) = PB

s ("^) = 1/[2(f(0)] = 1⁄2, so that each firm’s profits are 1/4. If firm A releases non-drastic

asymmetric information that the "A

1

 for the targeted group is greater than "^, with "A

k

 = ("^ - w1

"A

1

)/(1-w1) for all other groups, the demand facing the two firms is 

Given this distribution of R, one can also calculate the demand facing firm A if the
16

information is symmetric and non-drastic. It differs from (11) only by one term; the term involving

("A

1

 - "^)

2

 is absent in the symmetric case. Since that term is negative (because w1 < 1⁄2), this means

that, other things equal, QA is lower in the asymmetric case (consistent with Proposition 2).

However, since MQA

/MPA

 is the same in the two cases, we have

Lemma 1: For any given non-drastic "A

1

 > "^, firm A’s profit-maximizing price will be higher if the

information is symmetric than asymmetric, when ,ij is uniform on (0,1).

Proof: Firm A’s first-order condition with respect to its price in the asymmetric case equals

Evaluated at PA

 = PA

S ("A

1

, w1

), PB = PB

S ("A

1

, w1

), this equals 

and since PA

S = 1/(2(1- 2 w1

("A

1

 - "^)), this equals w1("A

1

 - "^)

2

 (2 w1 -1)/(2(1-w1)) which is negative.

It follows that evaluated at PB = PB

S ("A

1

, w1

), firm A’s profit-maximizing price is lower in the

asymmetric case. ,

Similarly, the expression for QB in the symmetric, non-drastic case differs from equation (12)

by the last term only. In equation (12), the last term is positive, which implies that the QB

 will be

higher in the asymmetric case. As was the case for firm A, the slope of firm B’s demand curve

does not change between the two cases. Hence,

Lemma 2: For any given non-drastic "A

1

 > "B

1

, firm B’s profit-maximizing price will be lower if the

information is symmetric than asymmetric when ,ij is uniform on (0,1). 
17

Proof: Follows same logic as Lemma 1.,

The intuition behind these lemmas is that compared to the symmetric case, asymmetric

information increases B’s sales and decreases A’s sales, without changing the slope of either firm’s

demand curve. Hence, for firm A, the number of marginal customers is the same whether a given

"A

1

 is symmetric or asymmetric, but the number of inframarginal consumers is lower in the

asymmetric case, leading firm A to charge a lower price (and conversely for firm B). Hence, while

the assumption that ,ij 

is uniform on (0,1) does not allow one to calculate equilibrium prices, it does

allow one to determine how the best-response functions differ between symmetric and asymmetric

cases. This in turn implies 

Proposition 4: Compared to the symmetric equilibrium, PA will be lower and PB will be higher with

asymmetric information for "A

1 non-drastic, when ,ij is uniform on (0,1).

Proof: Compared to the symmetric equilibrium, A’s best-response function is lower and B’s is

higher by equal amounts in the asymmetric equilibrium. This implies an increase in PB and a

decrease in PA

, since both best-response functions have slopes between 0 and 1. (

Figures 2 and 3 shows how A’s price and profits vary with the two parameters in the

symmetric and asymmetric non-drastic cases. These results illustrate Proposition 4 - both A’s prices

and profits are higher in the symmetric case. Figure 2 shows the prices in the two cases as functions

of w1

 for "A

1

 - "^

 = .5. Figure 3 indicates that, at this value of "A

1

- "^, profits in both cases are

increasing in w1 and that A’s profits are higher in the symmetric equlibrium. Although not depicted

there, B’s prices and profits are higher in the asymmetric case. Figure 4 shows the effect of higher

"A

1

- "^ on prices and profits (for w1 = .25). 
15Of course, if the targeted group is sufficiently large, and the change induced by the

information is sufficiently large, condition (6) is no longer satisfied, and firm A increases its

profits by revealing the information, and then selling to group 1 only.

18

Unfortunately, the relationship between the asymmetric and symmetric reaction curves in the

drastic case depends on the values of the two parameters. For example, when "A

1

 - "^

 = 1, prices and

profits are higher for both firms in the symmetric equilibrium than in the asymmetric one for all

values of w1

. In fact, for certain values of w1

, firm A’s profits with drastic asymmetric information

can actually be lower than in the initial, “no information” equilibrium. The reason is that drastic

asymmetric information increases a small group’s valuation of brand A by a large amount, while

reducing a large group’s value of it by a small amount. Since the density function is lower when

evaluated at higher values of *"A

k

 - "B

k

*, large changes in information have proportionately smaller

effects on sales than small changes.15 Hence, firm A’s sales fall, and even though its (absolute)

demand elasticity falls as well, the net effect on A’s profits could be negative. Figure 5 shows the

relationship between "A

1

 - "^

 and firm A’s prices and profits for w1 = .1. Note that in both the

asymmetric and symmetric equilibria, both prices and profits are increasing in "A

1

for "A

1

 - "^

 nondrastic (i.e., less than 1). However, for "A

1

 - "^

 > 1, A’s profits in the asymmetric case are decreasing

in "A

1

, and eventually firm A’s profits are below those in the no information equilibrium.

The direct implication of this analysis is that firm A may not have an incentive to disclose

targeted information, even if the generation and dissemination of that information is costless. This

contrasts with symmetric targeted information, which always increases revenue. While targeted

information can be both socially and privately productive, previous literature has shown that the

incentive to gather and disseminate this information may be excessive from a social perspective. The

next section reexamines this result for asymmetric information.
19

IV. Welfare Analysis

Revelation of matching information of the type discussed in sections II and III yields a social

benefit. The benefit results from consumers making more appropriate choices between brands.

However, the information may be costly for firm A to generate and disseminate, and hence the

welfare effect of the information is less clear. In this section, I consider whether the social gain to

the information necessarily exceeds its costs.

The reason that information may be privately optimal, while reducing welfare is that the

benefit to the firm of releasing the information comes about through its impact on prices. Because

price increases induce transfers from consumers to producers, private profitability does not insure

social desirability.

In fact, both A&R and M&S find that there is an excess incentive to provide matching

information. In the A&R model, consumers can, in lieu of actually searching, spend money to

acquire information about which brand best matches their tastes. Alternatively, they can search (e.g.,

visit retailers), in which case they observe both brand characteristics and prices. A&R show that

equilibrium prices are decreasing in the percentage of consumers who choose to visit retailers,

because search increases price competition between rival sellers. Because the marginal consumer

ignores the impact his decision to avoid search has on prices (and therefore ignores the resultant

transfer) there is excess information gathering. In M&S, firms can inform consumers of the match

between the consumer and the two brands, at a cost which is increasing in the number of informed

consumers. Again, for the marginal consumer the firms choose to inform, the social benefit of the

improved matching is less than the marginal cost of informing that consumer (because the firm
20

receives transfers from inframarginal consumers). 

The representation of information in the model presented here is somewhat different from

representations in the previous literature. This paper follows M&S in assuming that firms, rather

than individual consumers, make the decisions as to whether to acquire information (in contrast to

A&R). Hence, the assumption here is that consumers cannot take any action to improve their

estimates of "A

k

. One important feature (especially for welfare) of the analysis from sections II and

III that differs from the earlier work is that the size of the informed group is assumed exogenous in

this paper, and therefore cannot on the margin be affected by the firm’s actions. Hence, in this

model, the existence of the transfer does not necessarily imply excess production of information. 

A useful way of examining the divergence between social and private values of information

is to consider the external effect of information. The change in welfare from the information is )W

= )AA + )AB + )CS, where )Ai is the change in firm i’s profit, and ) CS in the change in consumer

surplus. If the external effect of the information, )AB + ) CS, is positive, then information that is

profitable for A to gather and disseminate is necessarily welfare enhancing. Hence, if )AB + )CS

is positive, then we can say that A has too little incentive to gather and disseminate information.

Conversely, if )AB + ) CS is negative, then A has too much incentive. The following example

indicates that, even in the symmetric case, there can be too little, or too much information generated.

Example 1: As in section III, let f(R) = 1 + R for R < 0 and 1 - R for R > 0, where the support of F(R)

is (-1,1). Consider symmetric drastic information such that all consumers are served. Because the

information is symmetric, "A

2

 - "^ is also drastic, and the external welfare effect can be written
21

Change in Consumer Surplus Change in Firm B’s Profits

Group 1 *

-1

0 (("A1

 - "^ +R) (1+R))dR - )P

= .5("A

1

 - "^ - 1) + 1/3 - )P

-1/4

Group 2 .5("A

1

 - "^ - 1) + 1/3 - )P 1/4 + )P

Other Groups -)P )P/2

Summed over all groups, the external change in welfare is 2w1

 [("A

1

 - "^ - 1)/2 + 1/3] - )P/2.

If "A

1

 - "^ = 1, then )P = w1/(1-2 w1), and the external change is simply 2 w1/3 - w1/(2(1-2 w1)).

This is positive for small w1 (less than .125), and negative for large w1 (> .125). Finally, since this

expression is increasing in "A

1

 - "^, it follows that information which changes expectations

dramatically is most likely to be underproduced.( 

This example shows that, even in the symmetric case, firm A may have too little, or too much

incentive to gather and disseminate information. If indeed the incentive to gather and disseminate

information is excessive, it means that the information may in total have negative social value, which

is a stronger result than in A&R and M&S (where production of information is only excessive on

the margin). 

One additional aspect of group size is worth noting. Information induces a transfer not only

from consumers to producers, but also between consumers. Those consumers fortunate enough to

be members of a group for whom "A

k

changes may become better matched to brands by virtue of the

information, and experience increases in their welfare. In contrast, any consumer in a group with

no informational change will be harmed by the information, due to a higher price. Since information

about large groups is more likely to be profitable for firms to gather and disseminate (see Proposition
22

2), small groups are more likely to be adversely affected by information.

Finally, I consider the welfare effects of asymmetric information. Because there is no closedform solution for prices in the asymmetric case, determining the external welfare effect of

asymmetric information is more difficult than for symmetric information. Nevertheless, some

observations can be made. First, as shown in section III, for non-drastic information A’s price rises

less for any "A

1

 when the information is asymmetric, rather than symmetric. Consequently, the

transfer associated with any non-drastic "A

1

 is smaller, so that the external effect is larger in the

asymmetric case (i.e., positive for a larger set of values for "A

1

 and w1). In the drastic case,

comparisons are more difficult. However, as Figure 5 demonstrates, some drastic information may

actually reduce revenue, so that even if the cost of generating and disseminating it were zero, it

would not be produced. In that case, there clearly is too little incentive for information generation.

In general, it would appear that underproduction would be more of an issue for asymmetric

information than for symmetric information. The following example helps illustrate this point.

Example 2 - Consider the specifications from Example 1, except here suppose the information is

asymmetric. The external welfare effect of the asymmetric information is

Change in Consumer Surplus Change in AB

Group

1

-1/4
23

Other

groups

To compare this expression to the symmetric case, suppose "A

1

 - "^ = 1 and w1 = .25. Then, "A

k

 - "^

= -1/3 for all other groups, and PA = .819, PB = .92. In that case, the external welfare effect is

 = -.236/4 + 3(.191)/4 = .336. Since the external effect was negative for these parameter values in

the symmetric case, this suggests that asymmetric information is more likely to have positive

external effects than symmetric information. 

V. Discussion

The analysis in sections II and III assumes that the average quality of a brand is unaffected

by the release of the targeted information. Hence, the news that a brand is particularly suited to a

specific group is assumed to mean that it is less suitable for other groups. This interpretation is

consistent with the analysis in A&R and M&S, and seems appropriate in some cases. For example,

for pharmaceuticals, a drug’s success rate in the overall population is established in the initial
24

clinical trials, so that a rational consumer should interpret an increase in the success rate of the drug

for a group to which she does not belong as a decrease in the likelihood the drug will work for her.

An alternative interpretation of targeted information is the news that a product is more

appropriate for the targeted group has no effect on the perceived value of that product to the

remaining population. In this case, the targeted information has two effects on consumers. It

increases the average quality of the product, while simultaneously increasing the extent of

differences across groups in the market. This latter effect was dealt with in sections II and III, while

the effects of increases in one firm’s quality are well-established (see, e.g., Tirole, 1988 at 296/7).

Hence, the implications of this alternative interpretation of targeted information on prices and

outputs can be readily discerned using the intuition from these other models.

In particular, the effects on prices of firm A’s targeted information depend on whether the

information is drastic. Drastic information shifts A’s reaction curve out, while it leaves B’s

unchanged (its first-order condition is simply multiplied by (1-w), leaving its optimal price

unaffected). Hence, drastic information leads to higher prices for both firms. In contrast, non-drastic

information leaves the demand for brand B from non-targeted groups unchanged, while reducing

the targeted group’s demand for it. Hence, non-drastic information shifts B’s reaction curve in, while

shifting A’s out, so that the net effect on both prices is ambiguous. However, under the F(R)

analyzed in sections III and IV, this information causes B’s price to fall while A’s rises.

While the model assumes that consumers know their own ,ij, I do not model how they learn

their ,ij’s. The model most readily lends itself to products which are “search” rather than

“experience” goods, as the model is not dynamic. Vaccines would constitute an ideal example of

such a product. In this case, an individual’s ,ij could be based on the side effect profile detailed in
25

the (FDA-mandated) product inserts, e.g. the disutility a consumer places on nausea. If the good is

an “experience” good, then ,ij could represent past experience with the brand. For example, the ,ij

could reflect a patient’s previous history with antibiotics for sinus infections When a large

percentage of patients have a significant history with the category of products, it is likely that the

variation in individual tastes within a group would be large compared to differences across groups,

so that e

-

 would be large compared to "A

L

 - "^ (i.e., information will tend to be non-drastic). 

VI. Conclusion

This paper explored the consequences of increasing the accuracy of information about

product characteristics. Specifically, revealing information about the suitability of a brand for

specific groups within the population induces better matching of consumers to brands. However,

because better matching may induce price increases, the information may not improve either

consumer or social welfare.

The goal of this paper was to examine how three features of the information can influence

the price and welfare consequences of its release. Of particular interest I find that the size of the

group to which the information pertains is an important determinant of its price effect. Holding the

information content of the message fixed (how much it changes expectations), the price effect of the

information increases more than proportionately with the size of the group. Hence, information that

pertains to a large group is most likely to be profitable to disseminate. This provides two related

reasons why it is disadvantageous to be a member of a small group. First, information relevant to

the small group is less likely to be profitable to the seller. Second, information which has no effect

on a specific group’s expectations about the brands typically makes members of that group worse
26

off. Since information is less likely to be produced for small groups, this implies that the

information that does get produced will tend to harm members of small groups.

A second relevant aspect of information is whether it is symmetric. Asymmetric information

generally leads to smaller price effects than symmetric information. In fact, asymmetric information

may actually lower prices and revenues relative to the no information equilibrium, whereas

symmetric information always raises prices and revenues. This implies that firms may choose not

to differentiate themselves, contrary to what is sometimes called (e.g., Tirole,1988 at 267)) the

“Principle of Maximum Differentiation.” Finally, the information content of a message is an

important determinant of its welfare consequences. Even though prices are non-decreasing in the

information content of the message, the welfare effects are increasing in the information content over

some range.

While this paper focuses on differentiation through information revelation, the results can

also apply to changes in objective characteristics. For example, suppose there are two important

features of a bicycle component; durability and weight, and different groups within the population

value these features differently (recreational riders vs. commuters vs. racers). Consider the

combination of durability and weight at which the utility of the median user in the population is

maximized, subject to the production function. Suppose that firm A’s rival has chosen this

combination of durability and weight, and that firm A can (at some cost) produce a slightly different

product (e.g., lighter, but less durable). This alternative product offers the same utility as the rival’s

product to most consumers in the population, but offers more utility to some groups, and less utility

to others. For the reasons discussed in this paper, such a change might be profitable because it can

increase the firm’s profit-maximizing price. Moreover, one can use the analysis in this paper to
27

show that the profitability of the change will be a function of the size of the group to whom this

variety appeals. That is, producing the variety preferred by a sub-population will be more profitable

if the sub-population is large, even if the additional total costs are proportional to group size.
28

References

Anderson, Simon and Regis Renault (2000) “Consumer Information and Firm Pricing: Negative

Externalities from Improved Information” International Economic Review, 41, pp. 721-42.

Grossman, Gene and Carl Shapiro (1984)“Informative Advertising and Differentiated Products”

Review of Economic Studies, 51, pp. 63-81.

Meurer, Michael and Dale Stahl (1994) “Informative Advertising and Product Match” International

Journal of Industrial Organization, 12, pp. 1-19.

Reinganum, Jennifer (1988) `The Timing of Innovation: Research, Development and Diffusion’ in

Richard Schmalensee and Robert Willig (eds) The Handbook of Industrial Organization.

Elsevier, Amsterdam, pp. 850-908.

Tirole, Jean (1988) The Theory of Industrial Organization MIT Press, Cambridge, MA. 

Welch, Finis (1979) “Effects of Cohort Size on Earnings: The Baby Boom Babies’ Financial Bust”

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