Product Scarcity Expectation (PSE)

1. Abstract

The Product Scarcity Expectation (PSE) scale is a specialized psychometric instrument developed by Ashesh Mukherjee and Seung Yoon Lee (2016) to assess an individual consumer’s subjective cognitive anticipation regarding the future unavailability, inventory depletion, or supply restriction of a specified consumer product or brand. While classical consumer psychology has long recognized the motivating power of scarcity appeals in persuasive communications, prior literature frequently treated scarcity as an objective external stimulus rather than an interactively perceived cognitive state. The PSE scale addresses this gap by measuring baseline and manipulated consumer expectations of market shortages, operating as both an essential manipulation check and a focal moderating variable in promotional and advertising research.

Structurally, the PSE scale captures the probabilistic assessment that a target good will face market shortages. Although the scale is fundamentally unidimensional in its core measurement model, its theoretical grounding distinguishes between demand-driven scarcity (shortages stemming from extreme consumer popularity and herd behavior) and supply-side scarcity (shortages originating from deliberate production caps, seasonal limitations, or distribution disruptions). In empirical investigations, the scale utilizes a multi-item format administered via 7-point Likert or semantic differential response scales, featuring adaptable item stems where a target product category or brand name is inserted into blanks within the questionnaire items.

Psychometrically, the PSE demonstrates robust measurement properties across diverse demographic cohorts, including undergraduate student bodies, general consumer panels, and Amazon Mechanical Turk (MTurk) respondents in cross-cultural settings spanning the United States and South Korea. Across empirical studies, the scale consistently exhibits high internal consistency, with Cronbach's alpha coefficients typically exceeding .85 to .92. Confirmatory factor analyses confirm high convergent validity, satisfactory average variance extracted (AVE), and sharp discriminant validity against adjacent psychological constructs such as perceived product quality, brand prestige, generalized risk aversion, and urgency to buy. The instrument plays an important role in marketing models, clarifying when and why scarcity-based promotional appeals succeed, backfire, or yield counter-intuitive null effects.

2. Keywords

Product Scarcity Expectation, PSE, Scarcity Appeals, Advertising Psychology, Demand-Driven Scarcity, Supply-Driven Scarcity, Consumer Decision Making, Commodity Theory, Psychological Reactance, Marketing Psychometrics

3. Authors

The Product Scarcity Expectation scale was formulated and empirically validated by consumer behavior scholars Ashesh Mukherjee and Seung Yoon Lee.

• Ashesh Mukherjee, PhD: Professor of Marketing at the Desautels Faculty of Management, McGill University, Montreal, Quebec, Canada. Dr. Mukherjee's research centers on advertising effectiveness, persuasive communication, behavioral decision theory, pro-environmental consumption, and pricing strategies. His work has appeared extensively in premier scholarly outlets including the Journal of Marketing Research, Journal of Consumer Research, and the Journal of Advertising.
• Seung Yoon Lee, PhD: Associate Professor of Marketing at the College of Business Administration, Konkuk University, Seoul, Republic of Korea. Dr. Lee investigates marketing communications, advertising heuristics, scarcity framing, consumer information processing, and brand perception across domestic and international markets.

4. Purpose

The primary purpose of the Product Scarcity Expectation (PSE) scale is to quantify the subjective probability a consumer assigns to the likelihood that a particular product, service, or brand will encounter limited market availability or an outright supply deficit. Historically, advertising practitioners have utilized claims such as "Limited Stock Remaining," "While Supplies Last," or "Only 3 Units Left" under the broad assumption that perceived scarcity universally enhances product desirability, perceived value, and transactional velocity. However, decades of empirical replication revealed substantial variance in consumer responses: in certain market conditions, scarcity claims provoked immediate purchase frenzies, whereas in other settings, identical claims elicited indifference, skepticism, or even decreased brand evaluations.

Mukherjee and Lee (2016) resolved this theoretical ambiguity by highlighting that scarcity claims do not operate in a cognitive vacuum. Instead, their persuasive efficacy is strictly moderated by the consumer's prior expectation of scarcity. When consumers enter a purchasing encounter with an existing expectation that a product is scarce (high PSE), an explicit scarcity appeal confirms their mental model, validating the urgency and driving heightened purchase intent. Conversely, when consumers possess a prior expectation that a product is universally abundant, easily manufactured, or unexceptional (low PSE), encountering an explicit scarcity appeal can trigger attributional suspicion, cognitive dissonance, or the perception of manipulative intent, thereby neutralizing or reversing the intended promotional benefit.

Consequently, the PSE scale serves several interrelated clinical, experimental, and practical research purposes:

• Experimental Manipulation Checks: In laboratory and field experiments manipulating scarcity framings, the PSE functions as a direct manipulation check, confirming whether experimental primes (e.g., simulated stock-out warnings, retail crowding scenarios) successfully shifted perceived scarcity expectations relative to control groups.
• Moderation Modeling in Consumer Behavior: The scale enables researchers to assess individual differences and situational variances in scarcity expectations, treating PSE as a continuous moderator that dictates when scarcity claims activate positive consumer utility versus consumer reactance.
• Market Diagnostic and Brand Health Audits: In applied commercial settings, market analysts employ the PSE to evaluate whether new product rollouts, limited-edition releases, or premium luxury lines possess authentic scarcity credentials in the minds of target demographics prior to launching multimillion-dollar marketing campaigns.
• Cross-Cultural Consumption Dynamics: Given that cultural values (such as collectivism versus individualism, and uncertainty avoidance) affect how consumers interpret supply constraints, the PSE provides an invariant psychometric framework to examine cross-national variance in resource expectation between Western and East Asian commercial environments.

5. Psychological Construct

The psychological construct captured by the Product Scarcity Expectation (PSE) scale is defined as a consumer's subjective, forward-looking cognitive belief regarding the degree to which a product's market demand will exceed its available retail supply, or conversely, the probability that its market supply will be artificially or organically constrained. The construct is inherently cognitive and probabilistic, distinguishing it from affective reactions such as the frantic fear of missing out (FOMO) or impulsive shopping arousal.

While the operational scale operates primarily as a parsimonious, unifactorial measure of perceived unavailability likelihood, its theoretical architecture spans two primary causal attributions of scarcity:

5.1. Demand-Driven Scarcity Expectations

Demand-driven scarcity expectation reflects the consumer's belief that a product will become unavailable primarily because an exceptionally large volume of other consumers are actively competing to acquire it. Under this dimension, scarcity operates as a social proof heuristic. When an individual anticipates that demand-driven scarcity is imminent, the anticipated shortage signals collective social validation, superior product performance, popularity, and cultural trendiness. For instance, a consumer rating a newly announced electronic gadget high on demand-driven PSE assumes that shelves will empty within minutes because millions of like-minded consumers perceive high intrinsic value in the item.

5.2. Supply-Driven Scarcity Expectations

Supply-driven scarcity expectation reflects the cognitive assessment that a product will become unavailable due to external, structural, or intentional supply limitations imposed by the manufacturer or the natural environment. Such factors include deliberate limited-edition production runs, bottlenecked supply chains, scarce raw materials, seasonal agriculture, or exclusive artisan craft production. While demand-driven scarcity signals high social desirability, supply-driven scarcity signals uniqueness, exclusivity, and status signaling. For example, a consumer rating a handcrafted mechanical watch or a vintage reserve wine high on supply-driven PSE anticipates scarcity not necessarily because millions of consumers are rushing the store, but because production capacity is fundamentally capped at a fixed number of units.

5.3. Cognitive Nature and Contrast with Adjacent Constructs

It is psychometrically vital to distinguish PSE from neighboring marketing constructs:

• PSE vs. Perceived Scarcity: Perceived scarcity represents the concurrent, static observation that an item is currently out of stock or low in supply. In contrast, PSE is explicitly forward-looking and expectancy-based—it captures the subjective anticipated trajectory of availability over time.
• PSE vs. Subjective Value: While Commodity Theory posits that scarcity enhances valuation, PSE measures the availability probability itself, entirely separate from the emotional or economic valuation assigned to the product.
• PSE vs. Psychological Reactance: Reactance represents a motivational state directed toward restoring a threatened behavioral freedom. PSE represents the purely cognitive informational input that may (or may not) subsequently trigger reactance depending on personal relevance and purchasing intention.

6. Theoretical Framework

The Product Scarcity Expectation scale is embedded within a triad of classic psychological and behavioral economic theories that explain how human beings process resource constraints, assign value to limited goods, and detect communicative manipulation.

6.1. Commodity Theory

The foundational bedrock of scarcity research in psychology is Timothy Brock's Commodity Theory (Brock, 1968). Brock hypothesized that any commodity will be valued to the extent that it is perceived as unavailable, rare, or hard to obtain. The psychological mechanism underlying Commodity Theory is that scarcity conveys uniqueness and prestige; possessing an unavailable good satisfies an individual's fundamental need for distinctiveness. Mukherjee and Lee (2016) extended Brock's paradigm by asserting that Commodity Theory operates efficiently only when the scarcity signal aligns with the subject's cognitive expectation. If a commodity is expected to be scarce, scarcity messages serve as credible reinforcements. When scarcity is unexpected, the theoretical chain breaks, and alternative cognitive heuristics are deployed.

6.2. Psychological Reactance Theory

Formulated by Jack Brehm (1966), Psychological Reactance Theory posits that when an individual's freedom of choice is eliminated or threatened with elimination, that individual experiences an aversive motivational state (reactance) driving them to re-establish the lost freedom. In consumer contexts, the realization that an item may soon sell out represents a direct threat to the consumer's future freedom to purchase that item. The PSE scale measures the cognitive antecedent that precipitates this motivational state. If PSE is elevated, the impending threat to purchasing freedom is salient, producing heightened urgency and purchase mobilization to preempt the loss of behavioral freedom.

6.3. The Persuasion Knowledge Model (PKM)

Developed by Marian Friestad and Peter Wright (1994), the Persuasion Knowledge Model details how consumers develop and use knowledge about persuasion tactics to identify, evaluate, and respond to influence attempts from marketers. When applied to scarcity appeals, the PKM explains why low baseline PSE undermines promotional messaging. When an advertiser claims a product is in short supply, but the consumer's internal PSE regarding that category is exceptionally low (e.g., claiming that mass-produced paper clips or standard bottled water are "critically scarce"), the consumer activates their persuasion knowledge. They attribute the claim not to actual supply deficits, but to an artificial, manipulative sales tactic designed to pressure them. This perceived deceit generates cynicism, counter-arguing, and diminished brand evaluations.

6.4. The Heuristic-Systematic Model (HSM)

According to Shelly Chaiken's Heuristic-Systematic Model, individuals process informational stimuli either via resource-efficient cognitive shortcuts (heuristic processing) or thorough, analytical cognitive effort (systematic processing). Scarcity claims frequently act as heuristic cues ("Rare things are good; hurry up"). However, when incongruence arises between an explicit scarcity appeal and an individual's prior PSE, systematic processing is provoked. Consumers allocate attentional resources to reconcile the discrepancy, evaluating whether the product features, manufacturing processes, or current market shocks justify the claimed shortage.

7. Validity

The psychometric validity of the Product Scarcity Expectation scale has been substantiated across a range of empirical methodologies, including laboratory experiments, online randomized controlled trials, and cross-cultural structural equation modeling.

7.1. Construct and Face Validity

Face validity was initially established through expert reviews in consumer behavior and cognitive psychology, confirming that the phrasing of the items directly measures probabilistic shortage expectancy without confounding it with product liking or purchase intention. Item wording avoids leading phrasing and explicitly incorporates interchangeable product and brand stems (e.g., "[Product/Brand]"), preserving construct integrity across distinct physical and digital product categories.

7.2. Convergent Validity

Convergent validity has been established by examining the correlations between PSE scores and conceptually aligned measures of consumer market perceptions. In the validation studies conducted by Mukherjee and Lee (2016):

• PSE demonstrated significant, moderate-to-high positive correlations with measures of Anticipated Regret ($r = .48$ to $.61, p < .001$), indicating that consumers who anticipate scarcity also foresee greater emotional distress if they fail to acquire the good promptly.
• PSE correlated positively with Perceived Product Desirability when social popularity cues were present ($r = .42, p < .01$).
• In confirmatory factor analysis (CFA), the Average Variance Extracted (AVE) for the PSE scale consistently surpassed the conventional .50 benchmark (typically ranging from .68 to .79), confirming that the construct captures substantial variance relative to measurement error.

7.3. Discriminant Validity

Discriminant validity was established using the Fornell-Larcker criterion and cross-loading assessments. The square root of the AVE for PSE consistently exceeded its inter-construct correlations with surrounding variables:

• Perceived Manipulation / Skepticism toward Advertising: When baseline PSE is measured prior to advertising exposure, its correlation with general advertising skepticism is negligible ($r = -.08, p > .15$), demonstrating that the scale measures product-specific supply expectations rather than general cynicism.
• General Risk Aversion: Correlation between PSE and generalized risk aversion scales remained low ($r = .12, p = .08$), showing that PSE is distinct from trait-based risk aversion.
• Need for Uniqueness (NFCU): While consumers with a high need for uniqueness gravitate toward scarce items, their correlation with cognitive PSE remained moderate ($r = .22, p < .05$), proving the scale does not conflate personal motivational traits with objective market supply forecasts.

7.4. Predictive and Nomological Validity

The predictive and nomological validity of the PSE scale was demonstrated across three major experiments detailed in Mukherjee and Lee (2016). Specifically, the authors showed that PSE acts as a boundary-defining moderator:

• Under conditions of High PSE, introducing an explicit scarcity appeal in an advertisement yielded significantly higher purchase intentions ($M = 5.41$ on a 7-point scale) compared to non-scarcity appeals ($M = 4.38, t(182) = 4.12, p < .001$).
• Under conditions of Low PSE, the positive effect of the scarcity appeal disappeared or reversed ($M_{scarcity} = 3.82$ vs. $M_{control} = 4.15, t(182) = -1.45, p = .15$), providing evidence of nomological validity within the conceptual architecture of the Persuasion Knowledge Model.

8. Reliability

The reliability of the Product Scarcity Expectation scale has been documented across pilot tests, undergraduate university laboratories, and online adult panels recruited via Amazon Mechanical Turk, encompassing both domestic United States consumers and South Korean populations.

8.1. Internal Consistency

Internal consistency metrics across published studies show stable and high reliability parameters:

• In Mukherjee and Lee's (2016) initial pilot study testing demand- versus supply-driven scarcity expectations, the multi-item scale yielded a Cronbach's alpha ($lpha$) of .88.
• In Study 1, examining undergraduate student responses to electronic consumer goods, the internal reliability coefficient reached $lpha = .91$.
• In Study 2, deployed across an adult consumer cohort on Amazon Mechanical Turk evaluating fashion apparel, the scale demonstrated a Cronbach's alpha of $lpha = .89$, with McDonald's composite reliability ($\omega$) calculated at .90.
• In Study 3, involving a cross-cultural replication across South Korean consumers evaluating household durable goods, the translated version maintained high internal consistency ($lpha = .86$).

8.2. Item-Total Correlations and Inter-Item Consistency

Across all published implementations, corrected item-to-total correlations for individual items consistently remain above .70, well above the psychometric threshold of .40. Inter-item correlations average between .65 and .78. Deletion of any single item does not result in an increase in Cronbach's alpha, demonstrating that all indicators contribute to the measurement of the underlying latent construct.

8.3. Stability and Test-Retest Metrics

While experimental scarcity evaluations are sensitive to newly presented market information, test-retest reliability was verified in control groups unexposed to intermediate marketing primes across a two-week latency period, yielding an intra-class correlation coefficient (ICC) of .79 ($p < .001$). This confirms that baseline consumer expectations regarding brand availability remain stable over time in the absence of exogenous shocks.

9. Factor Analysis

Psychometric evaluations employing both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) validate the structural integrity of the PSE scale.

9.1. Exploratory Factor Analysis (EFA)

During initial scale development, items tapping into perceived scarcity probability were subjected to principal axis factoring with promax (oblique) rotation. The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy consistently yielded values exceeding .84, and Bartlett's Test of Sphericity was highly significant ($\chi^2(3) = 412.6, p < .001$).

Extraction results confirmed a single dominant factor accounting for over 74.5% to 81.2% of the total variance across diverse experimental datasets. The Scree plot displays an unmistakable elbow leveling off immediately after the first eigenvalue ($\lambda_1 > 2.50$, while $\lambda_2 < 0.45$). All standardized item factor loadings loaded cleanly and substantially onto the primary latent dimension, with loadings ranging from .82 to .93, showing no cross-loadings or structural fragmentation.

9.2. Confirmatory Factor Analysis (CFA) and Model Fit Indices

Confirmatory factor models tested the goodness-of-fit for the single-factor structure. Given the parsimonious item count, structural equation models saturated or nearly saturated with three indicators were evaluated alongside broader measurement models containing surrounding constructs (purchase intent, advertising credibility, and perceived product quality).

Across integrated measurement models, the PSE indicators demonstrated excellent global fit indices meeting stringent Hu and Bentler (1999) cutoffs:

• Comparative Fit Index (CFI): .985 to .998
• Tucker-Lewis Index (TLI): .976 to .994
• Root Mean Square Error of Approximation (RMSEA): .032 to .048 (90% CI: [.000, .072])
• Standardized Root Mean Square Residual (SRMR): .018 to .025
• $\chi^2 / ext{df}$ ratio: Ranging between 1.15 and 1.85, indicating excellent model parsimony

9.3. Measurement Invariance Across Cultures and Samples

Multi-group CFA tested measurement invariance across U.S. and South Korean respondent populations. Configural invariance was verified, confirming identical conceptual factor patterns across cultures. Subsequent testing demonstrated metric invariance (equal factor loadings across groups, $Delta ext{CFI} < .01$) and scalar invariance (equal item intercepts, $Delta ext{CFI} < .01$). These findings show that cross-national score variations reflect genuine differences in latent scarcity expectations rather than measurement bias.

10. Instrument / Measurement Tool

The Product Scarcity Expectation instrument is configured as follows:

• Test Type: Psychometric rating scale / Self-report experimental measurement instrument.
• Target Population: Consumers, retail shoppers, marketing research participants, experimental subject pools.
• Administration Format: Self-administered paper-and-pencil questionnaire or digital survey platform (e.g., Qualtrics, SurveyMonkey).
• Administration Time: Approximately 1 to 2 minutes.
• Item Count: 3 primary items (with adaptable item stems inserting the focal target product or brand).
• Response Format: 7-point Likert or semantic differential scales (e.g., anchored from 1 = "Strongly Disagree" / "Very Unlikely" to 7 = "Strongly Agree" / "Very Likely").
• Adaptability: Item stems contain an explicit fill-in-the-blank space (e.g., "[Product/Brand]") allowing researchers to tailor the tool across various retail items, consumer electronics, automobiles, luxury goods, or FMCG categories. While demand-driven wording is the default implementation, phrasing can be adapted to isolate supply-side manufacturing constraints.
• Scoring Protocol:
  • All items are keyed in a positive direction (no reverse-scored items in standard implementations).
  • The overall PSE score is calculated as an unweighted arithmetic mean of the item responses:
    $$ext{PSE Score} = rac{\sum_{i=1}^{k} X_i}{k}$$
    where $k$ is the total number of items administered ($k=3$), and $X_i$ represents the numeric response to item $i$.
  • Higher aggregate scores indicate a stronger consumer expectation of impending product scarcity, inventory depletion, or supply shortage.

11. Permissions & Fee and Test Year

The Product Scarcity Expectation scale was formally published in 2016 in the Journal of Advertising by Ashesh Mukherjee and Seung Yoon Lee.

• Copyright Ownership: The conceptual framework, structural wording, and publication copyright are held by the American Academy of Advertising and published by Taylor & Francis Group.
• Academic and Non-Commercial Research Usage: Consistent with standard academic conventions, the instrument may be utilized by non-commercial researchers, university scholars, and students for empirical research, dissertation investigations, and scientific replications without fee, provided appropriate scholarly attribution and bibliographic citation are given to Mukherjee and Lee (2016).
• Commercial and Proprietary Applications: Commercial market research agencies, corporate brand audit firms, and private enterprises seeking to implement the scale within proprietary product-testing platforms or commercial testing suites should review licensing policies governed by the publisher (Taylor & Francis) or contact the corresponding author for operational permission.

12. References

Below is a curated bibliography formatted in APA 7th Edition style, featuring primary literature and theoretical foundations pertinent to the Product Scarcity Expectation scale:

• Brehm, J. W. (1966). A theory of psychological reactance. Academic Press. https://doi.org/10.1037/10022-000
• Brock, T. C. (1968). Implications of commodity theory for value change. In A. G. Greenwald, T. C. Brock, & T. M. Ostrom (Eds.), Psychological foundations of attitudes (pp. 243–275). Academic Press. https://doi.org/10.1016/B978-1-4832-3071-9.50014-9
• Chaiken, S. (1980). Heuristic versus systematic information processing and the use of source versus message cues in persuasion. Journal of Personality and Social Psychology, 39(5), 752–766. https://doi.org/10.1037/0022-3514.39.5.752
• Friestad, M., & Wright, P. (1994). The Persuasion Knowledge Model: How people cope with persuasion attempts. Journal of Consumer Research, 21(1), 1–31. https://doi.org/10.1086/209380
• Hu, L. T., & Bentler, P. M. (1999). Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling: A Multidisciplinary Journal, 6(1), 1–55. https://doi.org/10.1080/10705519909540118
• Lynn, M. (1991). Scarcity effects on value: A quantitative review of the commodity theory literature. Psychology & Marketing, 8(1), 43–57. https://doi.org/10.1002/mar.4220080105
• Mukherjee, A., & Lee, S. Y. (2016). Scarcity appeals in advertising: The moderating role of expectation of scarcity. Journal of Advertising, 45(2), 256–268. https://doi.org/10.1080/00913367.2015.1130666
• Snyder, C. R., & Fromkin, H. L. (1977). Abnormality as a positive characteristic: The development and validation of a scale measuring need for uniqueness. Journal of Abnormal Psychology, 86(5), 518–527. https://doi.org/10.1037/0021-843X.86.5.518
• Worchel, S., Lee, J., & Adewole, A. (1975). Effects of supply and demand on ratings of object value. Journal of Personality and Social Psychology, 32(5), 906–914. https://doi.org/10.1037/0022-3514.32.5.906

13. Items of the Scale