Chapter 13
Dashboards, Insight Communication and Managerial Decisions
Post Graduate Program in Advertising and Media
Campaign ROI & Analytics
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Post Graduate
Dashboards, Insight Communication and Managerial Decisions
Introduction
Campaign analytics creates value only when evidence changes a decision. A dashboard that displays hundreds of metrics may be technically impressive yet strategically useless if managers cannot identify what happened, why it happened, what is uncertain, and what should happen next. This chapter examines dashboards and reporting as managerial systems rather than as collections of charts. It focuses on the movement from measurement to interpretation and from interpretation to action.
In advertising and media, decisions are made under uncertainty. Audiences are fragmented, attribution is incomplete, platforms optimise toward different objectives, data may be delayed or modelled, and commercial outcomes often occur after the reporting period. Consequently, executive communication must balance speed with validity. The analyst's task is not merely to report a return-on-ad-spend figure; it is to explain the evidence, identify performance drivers, quantify limitations, and recommend an action consistent with organisational priorities and risk tolerance.
A useful reporting system connects five elements:
Strategic objective: the business or brand outcome sought.
Measurement design: definitions, data sources, attribution rules and time windows.
Performance evidence: descriptive and diagnostic metrics.
Decision logic: thresholds, trade-offs, scenarios and uncertainty.
Governance and action: ownership, timing, approval and follow-up measurement.
Learning Objectives
By the end of this chapter, the reader should be able to:
design an executive dashboard aligned with campaign objectives and managerial decisions;
distinguish descriptive, diagnostic, predictive and decision metrics;
select a limited set of leading and lagging indicators;
communicate uncertainty, data quality and attribution limitations;
explain performance through driver trees, segmentation and controlled comparisons;
convert findings into optimisation, investment and leadership recommendations;
establish reporting cadences, ownership and escalation rules; and
evaluate dashboards ethically, including privacy, fairness and governance risks.
1. Dashboards as Decision Systems
A dashboard is a governed interface that presents selected evidence for a defined audience, decision and time horizon. It is not synonymous with a visualisation tool. A chart becomes useful only when its meaning, source, refresh schedule, owner and decision consequence are clear.
Three dashboard levels are commonly required:
Level
Primary user
Time horizon
Typical purpose
Operational
Channel or campaign team
Daily to weekly
Detect delivery problems and optimise execution
Management
Marketing and commercial managers
Weekly to monthly
Allocate budget and assess progress toward targets
Executive
Senior leadership or board
Monthly to quarterly
Decide investment, risk appetite and strategic direction
The levels should use a consistent metric dictionary but different degrees of detail. An executive dashboard should not be a compressed operational dashboard. Executives require fewer measures, trend context, material exceptions, business implications and explicit decisions required. Operational teams need granular dimensions such as placement, audience, creative, frequency and bid strategy.
The decision-first design principle
Dashboard design should begin with questions rather than available data. Examples include:
Are we on track to achieve the qualified-lead target?
Which channels are generating incremental sales rather than merely attributed sales?
Should the next budget unit be invested in search, video or retail media?
Is a falling conversion rate caused by media quality, creative fatigue, price, landing-page friction or tracking failure?
What action should be taken this week, and what evidence would reverse that action?
Each question should have a decision owner, a decision deadline and a minimum evidence requirement. This prevents the common failure in which teams monitor metrics continuously but make decisions inconsistently.
Funnel layer: reach, qualified visits, leads, purchases and repeat behaviour.
Driver layer: spend, impressions, reach, frequency, cost, creative response, audience quality and site experience.
Data-quality layer: completeness, latency, reconciliation status, consent coverage and model version.
The data-quality layer is essential. A metric without a visible indication of freshness and reliability can create false confidence. A dashboard should distinguish zero from missing, preliminary from final, observed from modelled, and attributed from incremental results.
2. Metric Taxonomy: From Description to Decision
Metrics differ not only in what they measure but also in the role they play in reasoning.
Descriptive metrics
Descriptive metrics answer “what happened?” Examples include spend, impressions, reach, clicks, conversions, revenue and cost per acquisition. They are necessary but insufficient. A fall in conversions may reflect lower spend, weaker demand, tracking loss or a change in attribution rules.
Diagnostic metrics
Diagnostic metrics answer “why might it have happened?” Examples include click-through rate, landing-page conversion rate, frequency, audience overlap, video completion rate, auction competitiveness, stock availability and page-load time. Diagnostic metrics are explanatory clues, not automatically causal explanations.
Predictive metrics
Predictive metrics answer “what is likely to happen?” Examples include projected month-end revenue, expected conversions, propensity scores and forecasted marginal return. Predictions depend on assumptions and should be accompanied by intervals or scenario ranges where possible.
Decision metrics
Decision metrics answer “what should we do?” Examples include incremental return on marginal spend, expected contribution after media cost, probability of achieving a target, value at risk and the expected effect of reallocating budget. A decision metric combines evidence with an objective, constraint or preference.
A high click-through rate is not inherently a decision metric. It becomes relevant when it helps determine whether creative should be retained, provided that downstream quality is acceptable and the campaign objective values traffic.
Leading and lagging indicators
Lagging indicators, such as sales and profit, show realised outcomes. Leading indicators, such as qualified traffic, product-page engagement and checkout initiation, provide earlier signals. Leading indicators are useful only when their empirical relationship with later outcomes has been validated. Treating every early signal as predictive encourages premature optimisation.
Vanity and consequential metrics
A vanity metric may look impressive but have little relation to the decision, such as raw impressions without audience quality or business context. A consequential metric changes resource allocation or risk assessment. The distinction is contextual: reach may be consequential for a launch but secondary for a tightly constrained direct-response programme.
3. Metric Definitions and Mathematical Foundations
Consistent definitions are a prerequisite for credible reporting. The following formulas are common, but each has a limited interpretation.
Impression-based click-through rate is:
CTR = C ÷ I × 100
where C is clicks and I is impressions. The formula assumes that clicks and impressions refer to the same population, platform, period and counting rules. It measures observed response to served impressions; it does not measure sales effectiveness.
Conversion rate from clicks is:
CVR = V ÷ C × 100
where V is recorded conversions and C is clicks. It is meaningful only if the click and conversion windows, deduplication rules and tracking coverage are compatible.
Cost per acquisition is:
CPA = S ÷ V
where S is media spend in currency units and V is the number of defined acquisitions. CPA has currency per acquisition as its unit. It should not be compared across campaigns with materially different customer value unless value is incorporated.
Return on ad spend is:
ROAS = R ÷ S
where R is attributed revenue and S is media spend. ROAS is a ratio, often expressed as “4.0×”. It is not profit unless revenue is replaced by an appropriate profit or contribution measure and other costs are handled consistently.
Contribution after media cost may be expressed as:
Contribution after media = R × m − S
where m is the contribution margin rate after variable fulfilment and product costs, expressed as a decimal. The measure assumes that R is comparable revenue and that m is appropriate to the products and period.
For investment decisions, marginal rather than average return is often more relevant. If spend changes from S1 to S2 and contribution changes from K1 to K2, marginal contribution per additional currency unit is:
MCPM = (K2 − K1) ÷ (S2 − S1)
where MCPM is marginal contribution per media currency unit and S2 ≠ S1. This estimate is causal only if the change is evaluated using a credible experiment or a well-supported quasi-experimental design. Average ROAS cannot, by itself, establish the return on the next unit of spending.
Worked example
An online retailer spends £80,000 and records £320,000 in attributed revenue. Its contribution margin is 35%.
ROAS = 320,000 ÷ 80,000 = 4.0×
Contribution before media cost is 320,000 × 0.35 = £112,000. Therefore contribution after media cost is 112,000 − 80,000 = £32,000. The campaign appears efficient on a revenue basis, but its economic surplus after media is £32,000, not £320,000. If attribution is non-incremental, even this surplus may be overstated.
4. Explaining Performance: Driver Trees and Comparisons
A dashboard should help a manager move from an outcome to plausible drivers. A driver tree decomposes a high-level measure into interpretable components. For example:
Driver tree from revenue to media and conversion drivers
Figure: Driver tree from revenue to media and conversion drivers
Figure: Illustrative driver tree linking revenue to media, conversion and commercial drivers.
For a direct-response funnel, recorded conversions can be represented conceptually as impressions × click-through rate × post-click conversion rate, provided the stages are measured consistently. This identity is descriptive, not proof that changing one factor will cause a proportional change in conversions.
Comparison discipline
Performance should be compared against a relevant reference:
prior period, adjusted for seasonality and budget;
target or plan;
control or holdout group;
comparable audience, creative or market;
forecast or scenario; or
benchmark with compatible definitions.
“Up 20%” is incomplete without a denominator, period, statistical or practical significance, and explanation of what changed. A useful comparison asks whether the difference is large enough to matter commercially and credible enough to guide action.
Segmentation can reveal heterogeneous effects. However, excessive slicing creates false discoveries and unstable small samples. Analysts should predefine important segments, disclose sample sizes, and treat exploratory patterns as hypotheses until validated.
5. Communicating Uncertainty and Data Quality
Uncertainty is not a weakness in analysis; hidden uncertainty is. Campaign reports commonly contain several uncertainty sources:
sampling error in surveys and brand studies;
measurement error and missing conversion events;
attribution-model assumptions;
delayed or revised platform data;
confounding from promotions, price, distribution or competitors;
model uncertainty in forecasts and media mix models; and
structural changes such as privacy restrictions or platform algorithm updates.
Intervals and scenarios
For an estimate θ̂, an approximate confidence interval may be written as:
θ̂ ± z × SE(θ̂)
where SE(θ̂) is the standard error and z is a critical value determined by the desired confidence level under the model assumptions. The interval describes uncertainty in an estimation procedure; it does not guarantee that the true value lies within the interval, especially when systematic bias or model misspecification dominates sampling error.
For managerial communication, scenario ranges are often more useful than false precision. For example:
Scenario
Incremental revenue
Probability or confidence description
Decision implication
Conservative
£180,000
Tracking and incrementality concerns remain
Protect core spend
Base
£240,000
Most consistent with current evidence
Maintain and test
Upside
£300,000
Requires sustained response and supply
Scale conditionally
A scenario is not a probability distribution unless probabilities are actually estimated. Labels such as conservative, base and upside should be defined and linked to assumptions.
Data-quality annotations
Every important metric should ideally show:
source and owner;
last refresh time;
whether it is observed, modelled or attributed;
coverage and known missingness;
reconciliation status;
definition and denominator; and
material caveats.
A discrepancy between platform-reported conversions and verified orders is not merely a technical inconvenience. It changes the decision confidence and may alter the recommended spend.
6. Insight Communication for Different Audiences
An insight is more than an observation. A practical structure is:
Example: “Qualified-search conversion fell from 4.2% to 3.1% after the landing-page redesign. The decline is concentrated on mobile, where load time increased by 1.8 seconds. Because the timing and segment pattern are consistent, confidence is moderate, although the analysis is observational. Revert the mobile template for one week and run a controlled test. The web product owner should report results next Monday.”
This structure prevents three common errors: presenting correlation as causation, describing a problem without an action, and recommending action without specifying accountability.
Executive communication principles
Lead with the decision: state what approval, action or attention is required.
Use business language: translate media metrics into revenue, contribution, risk, customers or strategic progress.
Show trend and context: include target, prior period and relevant benchmark.
Make trade-offs explicit: growth may require accepting higher CPA; efficiency may reduce reach.
Separate facts from interpretation: label assumptions and hypotheses.
Report exceptions, not every observation: attention is a scarce managerial resource.
Give a confidence statement: high, moderate or low, with reasons.
Specify the next measurement: explain how the recommendation will be evaluated.
A strong executive page may contain a headline, three outcome indicators, two driver charts, one risk or uncertainty note, and two decisions required. Design should support rapid comprehension without encouraging simplistic interpretations.
7. Reporting Cadence and Operating Governance
A cadence defines when information is produced, discussed and acted upon. It should reflect decision latency rather than habit.
Cadence
Participants
Core questions
Typical outputs
Daily exception review
Channel operators
Is delivery broken or materially abnormal?
Fixes, alerts, data tickets
Weekly performance review
Marketing, media, creative, web
What changed and what should be optimised?
Tests, reallocations, hypotheses
Monthly business review
Marketing, finance, sales, product
Is investment creating economic value?
Budget decisions, forecast revision
Quarterly strategic review
Executive leadership
What should be scaled, stopped or redesigned?
Portfolio and capability decisions
A reporting calendar should identify a data cut-off, preliminary and final versions, meeting owner, decision rights and escalation thresholds. Finance and marketing should agree in advance how spend, revenue, refunds, cancellations, tax and contribution are treated. Otherwise, disagreement about definitions will dominate the meeting.
A useful governance device is a metric contract. It records the metric name, business definition, formula, source, owner, refresh rate, allowed dimensions, limitations and approved use. Metric contracts reduce silent changes that make trends incomparable.
8. Converting Findings into Managerial Decisions
Recommendations should be specific, conditional and economically grounded. Three common decision classes are optimisation, investment and leadership.
Optimisation decisions
These adjust execution: creative rotation, audience exclusions, bid limits, frequency controls, landing pages or channel mix. Optimisation should consider downstream value, not only cheap clicks. A practical recommendation includes the intervention, expected mechanism, test design, success metric, guardrail and review date.
Investment decisions
Investment decisions allocate scarce budget across channels, audiences or markets. They should consider marginal contribution, capacity, strategic learning value and risk. If channel A has higher average ROAS but channel B has stronger incremental evidence and available scale, the choice is not determined by average ROAS alone.
A simple constrained allocation problem can be represented as:
Maximise ∑ᵢ Kᵢ(Sᵢ) subject to ∑ᵢ Sᵢ ≤ B, Sᵢ ≥ 0
where Sᵢ is spend in channel i, Kᵢ(Sᵢ) is expected contribution, and B is the total budget. The function should normally show diminishing returns. The solution is only as credible as the response curves, incrementality estimates, constraints and assumptions used to construct them.
Leadership decisions
Leadership recommendations concern capability, risk and strategic direction: whether to invest in measurement infrastructure, reduce dependence on a platform, change agency governance, build first-party data capability or alter the brand-growth balance. Such decisions require evidence beyond short-term campaign metrics, including organisational capacity and long-term effects.
Decision memo format
A concise decision memo can include:
decision required;
recommendation;
evidence and key drivers;
expected benefit and cost;
risks and uncertainty;
alternatives considered;
owner and deadline; and
measurement and stop/scale criteria.
9. Illustrative Case: Northstar Homeware
Background
Northstar Homeware, a fictional omnichannel retailer, ran a six-week campaign for a premium kitchen range. The objective was profitable customer acquisition, with a secondary objective of reaching new households. The media budget was £600,000 across paid search, social video, connected television and retail media.
Problem
The executive dashboard showed social video with the lowest attributed CPA and connected television with almost no directly attributed orders. The initial proposal was to move 20% of connected-television budget into social video. The analytics lead questioned this conclusion because the dashboard used last-click attribution and did not report incrementality.
Analysis
The team established a common metric dictionary, reconciled orders with finance, and separated new from returning customers. It then reviewed reach, frequency, branded-search growth, geographic variation and the results of a prior regional holdout test. The holdout evidence suggested that connected television increased branded search and direct traffic, while social video generated efficient retargeting conversions but had substantial audience overlap with users already exposed to search.
The team constructed a driver view:
social video had strong click response among warm audiences;
prospecting social had weaker downstream conversion than retargeting;
connected television had high reach and moderate frequency but delayed effects;
retail media produced high conversion quality but was constrained by inventory; and
branded search captured demand generated by several channels, making last-click credit misleading.
The attribution report was therefore retained as a descriptive operational view, not as a causal budget-allocation rule. A regional holdout was extended for connected television, while social prospecting and retargeting were separated in the dashboard.
Approach and solution
Management approved three actions:
retain connected television at a reduced but protected level until the holdout produced a stable estimate;
shift budget within social from saturated retargeting to prospecting creative, subject to frequency and new-customer guardrails; and
increase retail-media investment only when inventory availability and marginal contribution met predefined thresholds.
The executive dashboard changed from a channel leaderboard to a decision view. It displayed incremental evidence where available, attributed results with a warning label, new-customer share, contribution after media, frequency, inventory constraints and confidence notes.
Outcome
In the following test period, attributed social CPA increased slightly because low-value retargeting volume was reduced. However, new-customer contribution improved, and the holdout indicated that connected television generated incremental demand that was not visible in last-click reporting. The organisation avoided an indiscriminate budget shift and created a repeatable test-and-learn process.
Learning points
The case demonstrates that:
the cheapest attributed acquisition is not necessarily the most valuable incremental acquisition;
channel metrics must be interpreted within the customer journey;
uncertainty should be attached to decisions, not hidden in technical appendices; and
a recommendation can preserve an option while evidence is collected, rather than forcing an immediate all-or-nothing choice.
10. Ethics, Privacy and Governance
Dashboards can amplify harm when they treat people as interchangeable data points or reward aggressive measurement practices. Key issues include:
consent and lawful processing of personal data;
purpose limitation and data minimisation;
re-identification risk in small segments;
discriminatory targeting or unequal delivery;
opaque platform optimisation;
use of sensitive attributes or proxies;
manipulation through selective benchmarks; and
executive decisions based on unverified model outputs.
Privacy-compliant analytics is not simply a legal checkbox. Consent status, retention periods, access permissions and aggregation thresholds should be visible in governance documentation. Small cells may need suppression, and analysts should avoid presenting individual-level predictions when aggregated evidence is sufficient.
Fairness should be evaluated when campaign delivery affects access to employment, credit, housing, health or other high-impact opportunities. Even in commercial advertising, exclusionary delivery can create reputational and social risks. A dashboard should identify whether performance differences are caused by legitimate audience strategy, unequal exposure, data bias or algorithmic allocation.
AI-generated summaries can improve reporting speed, but they require human review. An AI system may convert correlation into causal language, omit caveats, reproduce biased data patterns or hallucinate explanations. Approved use should include source traceability, version control, access restrictions and a named accountable reviewer.
11. Contemporary Developments and Best Practice
Privacy changes, signal loss, retail-media growth, connected television, clean rooms and automated buying are increasing the importance of triangulation. No single platform report should be treated as the complete truth. Strong measurement systems combine experiments, analytics, finance reconciliation, customer research and modelling according to the decision's importance.
Best practice includes:
begin with decisions and work backward to metrics;
keep executive dashboards deliberately small;
define every metric and protect definitions from silent change;
separate attributed, observed and incremental outcomes;
show data freshness and confidence;
use driver trees rather than unexplained scorecards;
compare against relevant controls and targets;
distinguish statistical significance from managerial significance;
use marginal economics for allocation decisions;
attach an owner, action and review date to recommendations;
preserve an audit trail of data, assumptions and revisions; and
retire metrics that no longer influence decisions.
A dashboard should be judged by the quality and timeliness of decisions it improves, not by the number of charts it contains.
Chapter Summary
Executive dashboards are decision systems that connect strategic objectives, measurement definitions, evidence, uncertainty and accountable action. Operational, management and executive dashboards require different levels of detail, although they should share governed definitions. Metrics should be classified as descriptive, diagnostic, predictive or decision-oriented, and leading indicators should be validated before being used as forecasts.
Core formulas such as CTR, CVR, CPA, ROAS and contribution after media are useful only when denominators, units, attribution windows and assumptions are clear. Average performance does not establish marginal or incremental value. Driver trees, segmentation and relevant comparisons help explain outcomes, but observational patterns should not automatically be interpreted as causal.
Effective communication states the observation, likely explanation, business implication, recommendation, confidence and accountability. Reporting cadences should match decision speed and include data cut-offs, metric contracts and escalation rules. Optimisation, investment and leadership recommendations must consider economics, constraints, uncertainty, strategic learning and risk. Privacy, fairness, auditability and human oversight are essential, particularly when AI and automated platforms influence measurement or delivery.
Key Terms
Dashboard: A governed interface that presents selected evidence for a defined audience and decision.
Metric contract: Documentation specifying a metric’s definition, formula, source, owner, refresh rate and limitations.
Descriptive metric: A measure that reports what happened.
Diagnostic metric: A measure used to investigate why an outcome may have occurred.
Predictive metric: A measure or estimate concerning what is likely to happen.
Decision metric: A measure designed to inform a resource, action or risk decision.
Leading indicator: An early signal associated with a later outcome.
Lagging indicator: A measure of an outcome after it has occurred.
Vanity metric: A metric that appears impressive but has limited decision relevance.
Driver tree: A structured decomposition connecting an outcome to contributing factors.
Attribution: The assignment of credit for an outcome to marketing touchpoints.
Incrementality: The causal effect produced by marketing beyond what would otherwise have occurred.
Marginal return: The additional outcome generated by an additional unit of investment.
Confidence interval: An interval produced by an estimation procedure to express sampling uncertainty.
Scenario analysis: Evaluation of outcomes under explicitly stated assumptions.
Reporting cadence: The planned rhythm for data production, review and decision-making.
Guardrail metric: A measure used to prevent optimisation from creating unacceptable side effects.
Data latency: The delay between an event occurring and becoming available for reporting.
Metric governance: Processes that control definitions, access, quality, changes and accountability.
Contribution after media: Contribution generated after subtracting media cost.
Review Questions
Short Answer Questions
Why is an executive dashboard not simply a smaller operational dashboard?
Distinguish a diagnostic metric from a decision metric.
State two reasons why attributed ROAS may not equal incremental economic return.
What information should accompany a materially uncertain forecast?
What is the purpose of a metric contract?
Long Answer Questions
Explain how a dashboard can be designed around decisions rather than available data. Illustrate your answer with an advertising example.
Discuss the role of driver trees, segmentation and comparison groups in explaining campaign performance.
Explain how reporting cadence and governance influence the quality of managerial decisions.
Compare optimisation, investment and leadership recommendations, including the evidence required for each.
Critically evaluate the ethical and governance risks of AI-assisted campaign reporting.
Analytical / Application Questions
A campaign records £150,000 of attributed revenue from £50,000 media spend. Its contribution margin is 30%. Calculate ROAS and contribution after media cost, then explain why these figures do not prove incrementality.
A channel’s attributed CPA is lower than another channel’s, but a holdout test shows that the second channel generates more incremental new customers. Design an executive dashboard view and recommend how budget should be considered.
A landing-page redesign is followed by a fall in mobile conversion rate, while desktop conversion is unchanged. Construct an observation–explanation–recommendation statement and specify a suitable validation test.
Multiple Choice Questions with Answers
Question 1
Which metric most directly supports a decision about whether to increase the next unit of media spending?
A. Total impressions
B. Average frequency
C. Incremental contribution per marginal spend
D. Cumulative clicks
Correct Answer: C. Incremental contribution per marginal spend
Question 2
A campaign spends £40,000 and records £160,000 in attributed revenue. What is its ROAS?
A. 0.25×
B. 2×
C. 4×
D. £120,000
Correct Answer: C. 4×
Question 3
Which statement best describes a diagnostic metric?
A. It reports the final approved budget
B. It helps investigate why an outcome changed
C. It guarantees a causal explanation
D. It replaces the business objective
Correct Answer: B. It helps investigate why an outcome changed
Question 4
What is the main purpose of a metric contract?
A. To increase the number of dashboard charts
B. To define ownership, calculation and limitations consistently
C. To eliminate all uncertainty from measurement
D. To ensure every platform uses identical data
Correct Answer: B. To define ownership, calculation and limitations consistently
Question 5
Which is the strongest reason to distinguish attributed from incremental outcomes?
A. Attribution always understates performance
B. Incrementality estimates what would not have happened without the intervention
C. Incrementality requires no comparison group
D. Attributed outcomes are never useful
Correct Answer: B. Incrementality estimates what would not have happened without the intervention
Question 6
A campaign generates £200,000 revenue, has a 40% contribution margin and costs £50,000 in media. What is contribution after media?
A. £30,000
B. £50,000
C. £80,000
D. £150,000
Correct Answer: A. £30,000
Question 7
Which practice best communicates uncertainty to executives?
A. Display all values to many decimal places
B. Hide model assumptions in an appendix
C. Show scenarios or intervals with assumptions and confidence notes
D. Use only the highest forecast
Correct Answer: C. Show scenarios or intervals with assumptions and confidence notes
Question 8
What is a guardrail metric used for?
A. To prevent an optimisation from causing unacceptable side effects
B. To replace all outcome metrics
C. To measure dashboard loading speed only
D. To increase attributed conversions automatically
Correct Answer: A. To prevent an optimisation from causing unacceptable side effects
Question 9
Which reporting cadence is generally most appropriate for strategic portfolio and capability decisions?
A. Continuous minute-by-minute monitoring
B. Daily exception review only
C. Quarterly strategic review
D. After every individual impression
Correct Answer: C. Quarterly strategic review
Question 10
Why can average ROAS be insufficient for budget allocation?
A. It has no unit
B. It cannot describe historical performance
C. It may not represent the return on the next marginal spend
D. It is always lower than CPA
Correct Answer: C. It may not represent the return on the next marginal spend