1. Foundations of Logistics and Supply Chain ManagementIntroduction and ContextLogistics and supply chain management (SCM) provide the physical, informational, financial, and relational foundations through which products and services reach users. A manufactured product has little economic value if it is unavailable at the required location and time. Likewise, a hospital’s clinical capability is weakened when medicines, equipment, information, or personnel are not available when needed. Logistics therefore concerns far more than transportation or warehousing. It is concerned with coordinating resources across space and time so that demand can be satisfied efficiently, reliably, and responsibly. The subject has strategic significance because supply chains connect organisations with suppliers, customers, regulators, communities, and the natural environment. Decisions about sourcing, inventory, transport, facilities, information systems, and service design influence cost, revenue, risk, resilience, customer experience, and sustainability. At postgraduate level, logistics should be understood as both an operational discipline and a systems-based managerial field. A useful starting point is to distinguish logistics from supply chain management. Logistics primarily manages the movement and storage of goods, services, and related information within and between organisations. Supply chain management has a broader scope: it coordinates organisations, processes, capabilities, and flows from sources of supply through transformation and distribution to the final user, including reverse flows. The distinction is analytical rather than absolute; logistics is a major component of SCM, while SCM integrates logistics with procurement, production, marketing, finance, product development, and relationship management. Learning ObjectivesAfter studying this chapter, students should be able to: 1. Define logistics, supply chain, and supply chain management accurately. 2. Explain the historical development and changing scope of logistics. 3. Identify the principal activities and flows in supply chains. 4. Apply systems thinking, value creation, and total cost analysis to logistics decisions. 5. Distinguish product, service, and humanitarian supply chains. 6. Evaluate stakeholder roles, trade-offs, risks, and ethical responsibilities. 7. Interpret the contribution of digital technologies and emerging practices. 8. Use foundational concepts to analyse a practical supply chain situation. From Physical Distribution to Integrated Supply ChainsThe earliest commercial logistics systems were associated with military provisioning, where armies had to move food, weapons, medical supplies, and personnel over difficult terrain. The term logistics is often linked to the organisation of such movements, although commercial logistics developed through later advances in trade, manufacturing, transport, and administration. During the industrial era, organisations increasingly separated production from consumption. Mass production created the need to distribute standardised goods through wholesalers, retailers, railways, ports, and warehouses. In the twentieth century, management attention initially focused on physical distribution: transportation, inventory, order processing, and warehousing after production. Purchasing and inbound materials management were often treated separately. The development of systems thinking changed this arrangement. Managers recognised that a decision that reduced one cost could increase another. For example, purchasing in large quantities may reduce unit purchase price but increase inventory, storage, obsolescence, and financing costs. Similarly, using a slower transport mode may reduce freight expenditure but increase stockout risk and customer dissatisfaction. The expansion of global sourcing, containerisation, information technology, outsourcing, e-commerce, and mass customisation further increased interdependence. Organisations could no longer manage logistics effectively as an isolated internal function. Suppliers, manufacturers, logistics providers, distributors, retailers, customers, and public agencies had to coordinate decisions. This broader integration is the foundation of contemporary supply chain management. Recent disruptions have also shifted attention from efficiency alone to resilience, agility, visibility, sustainability, and risk management. The objective is not simply to minimise cost under normal conditions, but to create a supply network capable of delivering acceptable performance under uncertainty and disruption. Essential Concepts and TerminologyA supply chain is a network of organisations, people, activities, resources, information, and technologies involved in creating and delivering a product or service. The term “network” is more accurate than a simple linear chain because organisations usually have multiple suppliers, customers, logistics providers, financial partners, and regulatory relationships. Logistics management is the planning, implementation, and control of the efficient and effective forward and reverse flow and storage of goods, services, and related information between an origin and a point of consumption in order to meet customer requirements. The definition highlights movement, storage, information, customer requirements, and the need to balance efficiency with effectiveness. Supply chain management is the coordinated management of supply chain relationships, processes, and flows to create value for customers and other stakeholders. It includes strategic sourcing, production, inventory, logistics, demand management, collaboration, performance measurement, and network design. A focal firm is the organisation whose supply chain is being examined. Upstream refers to activities and partners closer to sources of supply; downstream refers to activities and partners closer to the final customer. Tier-one suppliers provide goods or services directly to the focal firm, while tier-two suppliers serve tier-one suppliers. This distinction matters because risks may originate several tiers away from the focal firm. Customer service is the ability to meet customer requirements concerning availability, delivery speed, reliability, order accuracy, condition, flexibility, and information. Logistics performance is therefore multidimensional. A low-cost delivery that arrives late or damaged may not represent good performance. Efficiency concerns the relationship between outputs and resources used. Effectiveness concerns whether the desired objective is achieved. A warehouse may be efficient in processing many orders per employee but ineffective if it repeatedly ships incorrect items. Supply chain management seeks an appropriate combination of efficiency, effectiveness, responsiveness, resilience, and sustainability. The Activities That Make Logistics WorkAlthough the exact configuration varies by industry, logistics commonly includes customer service, demand forecasting, inventory management, order processing, materials handling, packaging, transportation, warehousing, facility location, purchasing coordination, information management, and reverse logistics. Transportation creates spatial utility by moving goods between locations. Mode selection involves trade-offs among cost, speed, reliability, capacity, accessibility, security, and environmental impact. Road transport often offers flexibility and door-to-door service; rail and water may provide economies for large volumes; air transport offers speed but generally at higher cost and environmental burden; pipelines are highly specialised for continuous flows. Warehousing creates time and place utility by holding, consolidating, sorting, protecting, and dispatching goods. Modern facilities may also perform postponement, labelling, kitting, returns processing, and light assembly. Warehousing is not merely storage: it is a coordination point between supply and demand. Inventory is a stock of materials, components, work-in-process, finished goods, or supplies held for future use. It can buffer uncertainty, support economies of scale, decouple stages, and improve service. It also ties up capital and creates risks of damage, deterioration, theft, obsolescence, and inaccurate records. Inventory decisions must therefore reflect demand variability, replenishment lead time, service requirements, item criticality, and supply risk. Order processing converts customer requirements into operational instructions. Accurate order entry, credit approval, allocation, picking, packing, dispatch, invoicing, and delivery confirmation influence the complete order cycle. Information quality is often as important as physical movement because errors in master data, forecasts, addresses, or inventory records generate costly rework. Packaging protects products, enables handling, supports unitisation, communicates information, and can influence sustainability. Packaging decisions must balance protection, material use, dimensions, labour, transport efficiency, product presentation, and regulatory requirements. Reverse logistics manages the movement of products, packaging, components, or materials from the user back to a point of recovery, resale, repair, recycling, or disposal. It is relevant to product returns, warranty claims, reusable containers, recalls, and circular-economy models. Supply Chain Flows and Value CreationSupply chains contain several interdependent flows. The physical flow moves materials, components, products, equipment, and waste. The information flow includes orders, forecasts, inventory status, shipment tracking, specifications, demand signals, and performance data. The financial flow includes payments, credit, invoices, insurance, duties, and financing arrangements. A fourth flow, often overlooked, is the flow of rights, responsibilities, and relationships: contracts, ownership, risk, compliance obligations, and decision authority move or change among parties. These flows are not independent. A customer order triggers information exchange, physical fulfilment, and financial settlement. Poor information can cause excess inventory or stockouts; delayed payment can weaken a supplier’s ability to maintain operations; unclear ownership can create disputes over damaged goods. Value is created when supply chain activities increase the usefulness of an offering for its intended user. Logistics contributes place utility, time utility, quantity utility, condition utility, and possession utility. A vaccine delivered at the correct temperature to a rural clinic creates more value than the same vaccine stored safely but unavailable where it is needed. In services, value may be created through availability, convenience, continuity, reliability, and reduced waiting time. The value proposition of a supply chain should be aligned with the customer segment. A luxury fashion retailer may prioritise presentation, availability, and rapid replenishment, while a commodity producer may prioritise low cost and consistent volume. A hospital may prioritise clinical availability and product traceability even when the unit price is not the lowest. Systems Thinking and the Logic of Trade-offsSystems thinking views the supply chain as an interconnected whole rather than a collection of independent departments. Its central question is not “Which function has the lowest cost?” but “How does this decision affect total system performance?” Local optimisation can produce global inefficiency. For example, a procurement department may choose a distant supplier offering a lower purchase price. The decision may be undesirable if it increases lead time, minimum order quantities, inbound transport, quality inspection, inventory, and disruption exposure. Similarly, a transport manager may consolidate shipments to reduce freight cost, but the resulting delay may increase lost sales or production downtime. Common trade-offs include: - transport cost versus delivery speed;
- inventory investment versus product availability;
- facility centralisation versus customer proximity;
- purchasing scale economies versus flexibility;
- standardisation versus customisation;
- efficiency versus resilience;
- low cost versus environmental and social performance;
- automation investment versus flexibility and implementation risk.
Trade-offs should not be treated as purely negative. Good design may reduce apparent conflicts through postponement, improved forecasting, standardisation, collaboration, cross-docking, modular product design, or digital visibility. The objective is to identify the relevant performance dimensions and evaluate alternatives over the entire system and time horizon. Total Cost AnalysisTotal cost analysis is a foundational method for logistics decision-making. It evaluates the combined cost consequences of a decision rather than focusing on one visible expenditure. A simplified logistics cost expression is: Total logistics cost = purchasing cost + transportation cost + warehousing cost + inventory carrying cost + order-processing cost + handling and packaging cost + quality and failure cost + risk and disruption cost − recovery value. The precise categories vary by decision. Inventory carrying cost can include capital cost, insurance, storage, shrinkage, deterioration, and obsolescence. Failure cost can include returns, penalties, emergency freight, lost sales, production stoppages, and reputational damage. A total-cost analysis should define the decision, establish the relevant time horizon, identify affected stakeholders, estimate cost and service impacts, test uncertainty, and compare alternatives. It should also distinguish fixed and variable costs, one-time and recurring costs, and direct and indirect consequences. Non-financial effects such as carbon emissions, worker safety, customer trust, and regulatory exposure may be incorporated through multi-criteria analysis even when they are not easily monetised. Total cost does not mean that every decision must be reduced to money. Rather, it prevents narrow financial measures from concealing important consequences. A higher-cost alternative may be justified when it materially improves safety, resilience, compliance, or service to vulnerable users. Stakeholders and Contexts of ApplicationA supply chain is governed by stakeholders with different objectives and power. Suppliers seek viable margins, predictable demand, fair payment, and reasonable requirements. Manufacturers seek reliable inputs and stable production. logistics providers seek efficient utilisation and commercially sustainable contracts. Distributors and retailers seek availability, speed, and inventory productivity. Customers seek value, reliability, and increasingly transparency. Governments regulate safety, trade, labour, competition, data, and environmental impacts. Communities experience employment, congestion, pollution, and emergency benefits or harms. Investors assess financial performance and risk. In product supply chains, physical transformation and distribution are prominent. Performance may be assessed through service level, fill rate, order cycle time, inventory turns, forecast accuracy, transport utilisation, and total landed cost. Service supply chains often involve simultaneous production and consumption, high customer participation, and limited ability to store service capacity. Examples include healthcare, education, tourism, banking, and repair services. Logistics may concern people, information, equipment, appointments, and consumables. In a hospital, the availability of beds, blood products, medicines, staff, diagnostic equipment, and information must be coordinated. Waiting time and continuity are central service outcomes. Humanitarian supply chains operate under urgency, uncertainty, damaged infrastructure, incomplete information, scarce resources, and ethical pressure. The objective is not commercial profit but the timely, equitable, and accountable delivery of relief and recovery assistance. Stakeholders include affected communities, governments, military or civil-protection agencies, donors, international organisations, local NGOs, transporters, and volunteers. Local knowledge and community participation are essential because externally designed solutions may be inappropriate or inaccessible. Humanitarian logistics illustrates why the “lowest cost” option is not always appropriate. A more expensive route may be necessary to reach an isolated community or protect aid workers. Allocation decisions also raise ethical questions of equity, vulnerability, transparency, and neutrality. A Framework for Analysing a Supply ChainA practical analysis can proceed through six questions. First, what customer or humanitarian need is being served? Second, who are the actors and what capabilities or constraints do they possess? Third, what physical, information, financial, and responsibility flows connect them? Fourth, where are value, cost, delay, uncertainty, and risk introduced? Fifth, which performance objectives conflict, and how should trade-offs be evaluated? Sixth, what governance, technology, collaboration, and improvement mechanisms are appropriate? This framework prevents premature solutions. For example, implementing a tracking system before clarifying processes may digitise confusion rather than improve performance. Similarly, adding inventory may conceal poor supplier reliability without addressing its cause. Illustrative Case: MedLine Community Health Supply NetworkBackgroundMedLine is a fictional regional health authority serving urban and rural clinics. It procures essential medicines from several manufacturers, stores them in a central distribution centre, and delivers them to 38 clinics. Some medicines require temperature control, while others have short or variable shelf lives. Situation and ProblemClinics report frequent stockouts of high-use medicines despite a rising total inventory value. Emergency shipments are common, expiry losses are increasing, and rural clinics receive less reliable service than urban clinics. Procurement measures performance mainly through purchase price, while transport is managed separately by a contracted carrier. Inventory records are updated manually at several points. AnalysisThe problem is not simply insufficient inventory. The network contains conflicting local objectives. Procurement buys in large batches to obtain price discounts; the central warehouse stores excess stock; clinics hold safety stock because replenishment is unreliable; and transport consolidates deliveries to reduce cost, increasing rural lead times. Manual records reduce visibility, while demand patterns differ significantly among clinics. A total-cost and service analysis identifies purchase price, expiry, emergency freight, stockout consequences, cold-chain risk, and staff time as relevant factors. The analysis also recognises that a medicine stockout can have a greater social cost than a comparable stockout of a non-critical item. Approach and StrategyMedLine classifies items by clinical criticality, demand variability, value, and temperature sensitivity. It introduces minimum and maximum inventory policies suited to each category, cycle counting for critical items, and electronic recording at receiving, picking, and delivery. Suppliers provide advance shipment information and batch-expiry data. The authority establishes differentiated delivery frequencies: predictable scheduled deliveries for rural clinics and additional replenishment for high-variability items. Procurement evaluates total landed cost and service risk rather than unit price alone. A small regional buffer is retained for critical medicines, but low-risk products are consolidated. Clinic staff participate in setting service priorities, and a dashboard monitors stockout days, expiry value, order accuracy, delivery reliability, and emergency shipments. OutcomeThe redesigned system is expected to reduce avoidable emergency shipments and expiry while improving availability of clinically critical medicines. The principal lesson is that inventory, procurement, transport, information, and service policy must be designed together. The case also shows that healthcare logistics requires ethical prioritisation: the most important item is not necessarily the most expensive item. Learning Points1. Local cost reductions can increase total system cost. 2. Product criticality should influence service and inventory policy. 3. Data quality is a process and governance issue, not only a software issue. 4. Humanitarian and public-service settings require equity and accountability alongside efficiency. 5. Cross-functional and stakeholder collaboration is necessary for sustainable improvement. Risks, Limitations, and Common MistakesSupply chains face demand uncertainty, supplier failure, transport disruption, geopolitical instability, cyberattack, quality problems, fraud, labour shortages, extreme weather, regulatory changes, and reputational damage. Concentrating supply can reduce transaction cost but increase dependency. Excessive decentralisation can improve responsiveness but weaken control and economies of scale. Common mistakes include measuring departments rather than end-to-end performance, treating forecasts as facts, ignoring tier-two and tier-three dependencies, selecting suppliers on price alone, increasing inventory without diagnosing variability, adopting technology without process redesign, and overlooking reverse flows. Another mistake is assuming that resilience means holding large stocks everywhere. Resilience may instead involve alternate suppliers, flexible capacity, modular products, visibility, scenario planning, and rapid recovery capability. Models and analyses also have limitations. Cost estimates may be uncertain, data may be incomplete, and benefits such as trust or resilience may be difficult to value. A mathematically optimal solution can be operationally impractical or socially unacceptable. Managerial judgement, consultation, sensitivity analysis, and periodic review are therefore essential. Ethics, Governance, and Professional ResponsibilityLogistics decisions distribute benefits, risks, and opportunities. Ethical supply chain management requires attention to forced labour, unsafe working conditions, discrimination, corruption, modern slavery, environmental damage, misleading claims, and unfair contractual practices. Supplier codes are insufficient unless supported by due diligence, meaningful audits, worker voice, corrective action, and responsible purchasing practices. Governance clarifies who has authority, how decisions are escalated, how performance is measured, and how information is shared. Contracts should address quality, service, data protection, liability, continuity, ethical conduct, and termination arrangements. In humanitarian settings, governance must also support impartiality, accountability to affected populations, safeguarding, and protection of sensitive information. Digital Applications and Emerging DevelopmentsEnterprise resource planning systems, warehouse management systems, transport management systems, barcode scanning, radio-frequency identification, sensors, electronic data interchange, and cloud platforms improve coordination and visibility. Analytics can support demand sensing, inventory segmentation, route planning, supplier risk monitoring, and scenario analysis. Artificial intelligence may assist forecasting, anomaly detection, document processing, and dynamic scheduling, but its outputs depend on data quality and appropriate human oversight. Digitalisation introduces risks: cyberattacks, system outages, data misuse, algorithmic bias, excessive surveillance, vendor dependency, and weak interoperability. Technology should therefore be selected according to a clearly defined operational problem, with controls for access, continuity, validation, privacy, and accountability. Emerging supply chain priorities include circularity, low-carbon logistics, regional and multi-sourced networks, supply chain finance, product traceability, autonomous operations, and collaborative planning. These developments do not eliminate foundational principles. They increase the importance of accurate data, process discipline, cross-organisational trust, and systems thinking. Best Practices for Foundational Supply Chain ManagementEffective organisations generally align supply chain design with the value proposition; map end-to-end flows; segment products, customers, and suppliers; use total-cost and total-value analysis; establish shared performance measures; maintain accurate master data; develop risk and continuity plans; collaborate with important partners; incorporate sustainability and ethics into decisions; and review performance through learning rather than blame. A balanced scorecard may combine customer outcomes, operational reliability, financial performance, resilience, environmental impact, workforce safety, and social responsibility. No single metric captures supply chain health. The quality of management lies in understanding relationships among measures and acting on root causes. Chapter SummaryLogistics coordinates the movement, storage, handling, and information associated with goods and services, while supply chain management integrates these activities across organisational boundaries. Modern supply chains are networks containing physical, information, financial, and responsibility flows. They create value by providing availability, speed, condition, convenience, and reliability. Systems thinking is essential because supply chain decisions generate trade-offs. Total cost analysis prevents managers from pursuing narrow local savings that create larger costs elsewhere. Product, service, and humanitarian supply chains share foundational principles but differ in their outputs, constraints, stakeholders, and ethical priorities. Effective management requires visibility, collaboration, appropriate technology, resilience, sustainability, and accountable governance. The central managerial task is to design and coordinate the network so that it serves its intended users while balancing cost, service, risk, and broader societal impact. Key TermsSupply chain: A network of organisations, resources, activities, and relationships involved in creating and delivering a product or service. Supply chain management: Coordinated management of supply chain relationships, processes, and flows to create value. Logistics management: Planning, implementing, and controlling the movement and storage of goods, services, and related information. Focal firm: The organisation whose supply chain is being analysed. Upstream: Supply chain activities and partners closer to sources of supply. Downstream: Supply chain activities and partners closer to the final customer. Tier-one supplier: A supplier that provides goods or services directly to the focal firm. Inventory: Stock of materials, components, work-in-process, finished goods, or supplies held for future use. Customer service: The ability to meet requirements for availability, speed, reliability, accuracy, condition, and information. Reverse logistics: Management of flows from users back to recovery, repair, recycling, resale, or disposal points. Physical flow: Movement of materials, products, equipment, and waste through a supply network. Information flow: Exchange of orders, forecasts, specifications, status data, and performance information. Financial flow: Movement of payments, invoices, credit, insurance, and related financial obligations. Systems thinking: Analysis of interdependencies and total system effects rather than isolated functions. Total cost: The combined cost consequences of a decision across relevant logistics and supply chain categories. Resilience: The ability of a supply chain to prepare for, absorb, adapt to, and recover from disruption. Postponement: Delaying final configuration, packaging, or differentiation until demand information is clearer. Service supply chain: A supply network that coordinates resources and processes to deliver services. Humanitarian logistics: Logistics supporting relief, recovery, and assistance under conditions of urgency and uncertainty. Supply chain visibility: The ability to access and interpret relevant information about flows, events, and conditions across the network. Review QuestionsShort Answer Questions1. Distinguish logistics management from supply chain management. 2. What are the four major flows found in supply chains? 3. Explain the difference between efficiency and effectiveness. 4. Why does inventory create both value and cost? 5. What is meant by reverse logistics? Long Answer Questions1. Explain the historical movement from physical distribution to integrated supply chain management. 2. Discuss how systems thinking helps managers handle logistics trade-offs. 3. Explain the role of total cost analysis in sourcing and transportation decisions. 4. Compare product, service, and humanitarian supply chains. 5. Discuss the ethical and governance responsibilities of supply chain professionals. Analytical / Application Questions1. A company reduces purchase price by switching to a distant supplier, but lead times and emergency freight increase. Analyse the decision using total cost and systems thinking. 2. Design a basic supply chain performance framework for a hospital that includes service, cost, resilience, ethical, and sustainability measures. 3. A disaster-response agency has limited stock and damaged roads. Explain how it should prioritise stakeholders, flows, technology, and trade-offs when designing its distribution approach. 22. Multiple Choice Questions with AnswersQuestion 1Which statement best distinguishes supply chain management from logistics management? A. Logistics concerns suppliers, while supply chain management concerns only customers. B. Supply chain management has a broader coordinating scope that includes logistics and inter-organisational relationships. C. Logistics is strategic, while supply chain management is exclusively tactical. D. There is no meaningful distinction between the two concepts. Correct Answer: B. Supply chain management has a broader coordinating scope that includes logistics and inter-organisational relationships. Question 2A procurement department selects a supplier with the lowest unit price, but the supplier requires large orders and long lead times. Which analysis is most appropriate? A. Compare only the quoted purchase prices. B. Measure warehouse labour productivity only. C. Apply total cost analysis, including inventory, transport, risk, and service effects. D. Ignore lead time because it is a supplier issue. Correct Answer: C. Apply total cost analysis, including inventory, transport, risk, and service effects. Question 3Which example primarily represents an information flow? A. Movement of components from a factory to an assembly plant B. Payment from a retailer to a distributor C. Transmission of an advance shipment notice to a receiving warehouse D. Return of damaged goods to a supplier Correct Answer: C. Transmission of an advance shipment notice to a receiving warehouse Question 4Why can local optimisation damage overall supply chain performance? A. Every department always has identical objectives. B. A local saving may create larger costs or service failures elsewhere in the system. C. Local decisions never influence other organisations. D. Supply chains do not contain trade-offs. Correct Answer: B. A local saving may create larger costs or service failures elsewhere in the system. Question 5Which logistics activity most directly creates time utility? A. Holding and positioning inventory so it is available when required B. Negotiating a lower supplier price C. Designing a product logo D. Auditing financial statements Correct Answer: A. Holding and positioning inventory so it is available when required Question 6A hospital gives priority to maintaining availability of a low-priced but clinically critical medicine. What principle does this illustrate? A. Unit price should always determine priority. B. Clinical criticality and stakeholder consequences should influence supply decisions. C. Humanitarian and service supply chains should use no inventory. D. Efficiency is the only valid performance objective. Correct Answer: B. Clinical criticality and stakeholder consequences should influence supply decisions. Question 7Which situation is the clearest example of reverse logistics? A. Shipping raw materials to a production facility B. Forecasting next month’s customer demand C. Returning reusable containers from customers for cleaning and refilling D. Paying a carrier for an outbound delivery Correct Answer: C. Returning reusable containers from customers for cleaning and refilling Question 8What is a major limitation of using a mathematically optimal supply chain model? A. Models can never represent costs. B. An optimal result may depend on incomplete data or assumptions and may be operationally or socially impractical. C. Models eliminate the need for managerial judgement. D. Mathematical models always increase disruption risk. Correct Answer: B. An optimal result may depend on incomplete data or assumptions and may be operationally or socially impractical. Question 9Which practice best supports supply chain resilience? A. Dependence on one low-cost supplier in one location B. Eliminating all safety stock regardless of product criticality C. Combining visibility, alternative capabilities, continuity planning, and recovery arrangements D. Measuring only average purchase price Correct Answer: C. Combining visibility, alternative capabilities, continuity planning, and recovery arrangements Question 10Why should technology implementation normally follow process and governance analysis? A. Technology cannot collect information. B. Digitising unclear or poorly controlled processes may automate errors rather than improve performance. C. Technology is irrelevant to logistics. D. Governance prevents all forms of automation. Correct Answer: B. Digitising unclear or poorly controlled processes may automate errors rather than improve performance.
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