Maintaining optimum stock levels is a critical function within procurement management, ensuring that organisations hold sufficient inventory to meet demand without incurring excessive holding costs or stockouts. In Kenya’s dynamic business environment, where supply chain disruptions and fluctuating demand are common, procurement professionals must skillfully balance stock availability and cost efficiency. This chapter explores methods for maintaining optimal inventory levels and the role of demand forecasting in achieving this balance, providing practical insights relevant to procurement managers in sectors such as healthcare, education, banking, and retail.

5.1 Maintenance of optimum stock levels

Maintaining optimum stock levels involves continuously monitoring and adjusting inventory to align with organisational needs, market conditions and operational capacities. Optimum stock is enough to meet demand without interruption, but not so much that money, space and goods are wasted. Effective stock maintenance prevents lost sales and production stoppages, reduces wastage from expired or obsolete goods, and frees up working capital. It combines inventory control techniques, supplier coordination and data analysis, and depends on accurate stock records, which are kept correct through stocktaking and stock verification.

Principles of maintaining optimum stock levels

The foundation of maintaining optimum stock levels is understanding the balance between supply and demand, cost minimisation and service level. The principles guiding this process include:

• Right quantity availability: Holding the amount of stock needed to meet customer or production needs without overstocking, which ties up capital unnecessarily.
• Timely replenishment: Scheduling orders to arrive before stock reaches critically low levels, preventing stockouts and operational delays.
• Cost efficiency: Balancing ordering costs, holding costs and shortage costs to minimise total inventory cost.
• Quality control: Maintaining stock quality by preventing damage, obsolescence or expiry through proper storage, handling and rotation.
• Continuous monitoring: Using inventory records, stock counts and verification to track stock movement and adjust reorder points as conditions change.

Stock control methods used to maintain optimum levels

• Reorder point system: Replenishment is triggered when stock falls to a set level that allows for lead time and demand variability.
• Periodic review system: Stock is reviewed at fixed intervals and orders are placed to bring stock back to a target level.
• Economic order quantity (EOQ): The order size that minimises the combined ordering and holding costs.
• Just-in-time (JIT): Deliveries are scheduled to coincide with production or use, reducing holding costs but requiring reliable suppliers.
• ABC analysis: Items are grouped by the value of their annual usage so that the tightest control and most frequent counting go to the high-value A items.

Challenges in maintaining optimum stock levels and mitigation strategies

• Demand forecasting errors: Inaccurate predictions lead to overstocking or stockouts. Mitigation: review forecasts regularly and combine several forecasting methods.
• Supplier disruptions: Late or poor-quality deliveries upset stock plans. Mitigation: develop more than one reliable supplier and agree clear delivery schedules.
• Storage limitations: Inadequate or poor storage space causes deterioration and limits stock that can be held. Mitigation: improve storage facilities and layout.
• Obsolescence: Changes in technology or market preferences make stock unusable. Mitigation: rotate stock on a first in, first out basis and review slow-moving items regularly.
• Cost and budget constraints: Changes in prices, holding costs or available funds affect the stock that can be held. Mitigation: monitor cost trends and set aside contingency funds for critical items.
• Theft and pilferage: Losses reduce actual stock below the recorded figure, so reorders are made too late. Mitigation: tighten security and access control and verify stock regularly.
• Inaccurate stock records: Errors in receipts and issues give false balances. Mitigation: use inventory management software, post transactions promptly and carry out regular stocktaking and verification.

5.1.1 Stock taking

Stocktaking is the physical counting, weighing or measuring of all goods held in the stores at a given time and the recording of the results on stock sheets. The counted quantities are then compared with the balances in the bin cards and stores ledger. It is the main way of confirming that the stock shown in the records actually exists, and it gives the stock figure used in the financial statements.

5.1.1.1 Meaning of stock take

A stock take is the process of physically identifying, counting and recording every item of stock held at a particular date, and valuing it. The result is a list of all items with the quantities found, which is compared with the recorded balances to find surpluses and shortages. For example, a Kenyan hardware wholesaler carries out a full stock take at its financial year end, counting every bag of cement, length of pipe and tin of paint in its warehouse.

5.1.1.2 Process of stock take

1. Plan the stock take: set the date and time, decide the approach, prepare a timetable and inform suppliers, customers and departments of any stoppage of receipts and issues.
2. Prepare the stores: arrange and label goods, put goods in their correct locations, separate damaged, obsolete and other people's goods, and clear pending documents.
3. Freeze or control movement: stop or strictly record receipts and issues during the count, and note the last GRN and issue voucher numbers before the count (cut-off).
4. Brief and organise the teams: assign each pair of counters an area, give them pre-numbered stock sheets and explain the counting and recording rules.
5. Count and record: one person counts, weighs or measures, and the other records the description, code, location, unit of measure, quantity and condition on the stock sheet. Counted locations are marked.
6. Check the count: supervisors or a second team recount a sample of items, and all high-value items, to confirm accuracy.
7. Compare with records: quantities on the stock sheets are compared with bin cards and the stores ledger, and differences (surpluses and shortages) are listed.
8. Investigate differences: recount items with large differences and check documents for unposted receipts or issues and recording errors.
9. Value the stock: multiply the agreed quantities by the unit cost using the organisation's valuation method.
10. Report and adjust: prepare a stocktaking report with the results and causes of differences, obtain approval and post stock adjustments to the records.

5.1.1.3 Importance of stocktaking

• Confirms existence of stock: It proves that the stock shown in the records is physically present.
• Corrects stock records: Errors in bin cards and ledgers are found and corrected, so reorder decisions are based on true balances.
• Detects losses and fraud: Shortages reveal theft, pilferage or unrecorded issues and support investigation.
• Identifies damaged, obsolete and slow-moving stock: The physical inspection shows items for disposal or special action.
• Provides the stock value for the accounts: The closing stock figure is needed for the financial statements and audit.
• Checks the efficiency of stores staff: Accurate results show good stores management; frequent differences show weaknesses.
• Supports insurance claims: An up-to-date stock figure shows what was held in case of fire or theft.

5.1.1.4 Advantages and disadvantages of stock taking

Advantages:

• Accurate records: Records are brought into line with physical stock.
• Control of losses: Staff know their stock will be counted, which discourages theft and carelessness.
• Reliable financial information: The stock value in the accounts is supported by a physical count.
• Better stock decisions: True balances help avoid both overstocking and stockouts.
• Improved housekeeping: Preparation for the count leaves the store tidy and well arranged.

Disadvantages:

• Disruption of operations: Receipts and issues may be stopped or slowed during a periodic stock take, affecting customers and production.
• Cost: It uses many staff hours, often with overtime, and may need extra staff.
• Errors under pressure: Large counts done in a short time can lead to counting and recording mistakes.
• Late discovery of problems: If done only once a year, losses and errors may go unnoticed for months.
• Staff fatigue and resentment: Long counting sessions over weekends or holidays can lower morale.

5.1.1.5 Approaches of stock taking

• Periodic stocktaking: All items are counted at one time, usually at the end of the financial year or half-year. Operations are often stopped during the count. It gives a complete picture at one date but disrupts work and finds errors late.
• Continuous (perpetual) stocktaking: A few items are counted every day or week throughout the year, so every item is counted several times a year without stopping operations. It finds errors early and spreads the workload, but needs dedicated staff.
• Cycle counting: A planned form of continuous counting in which items are counted at frequencies set by their importance, for example A items monthly, B items quarterly and C items twice a year.
• Spot checks (surprise counts): Selected items, often high-value or attractive ones, are counted without warning to discourage theft and to test the records.
• Sample counting: A random sample of items is counted, and the accuracy found is used to judge the reliability of the whole record.

5.1.1.6 Nature of preparation for stock taking

Good preparation decides the accuracy of a stock take. Preparation covers people, goods, documents and timing.

• Planning and scheduling: Fix the date, time and duration, choose the approach and inform all departments, suppliers and customers affected.
• Appointment of teams: Select counters, recorders and supervisors, and include people independent of the stores, such as internal audit, for objectivity.
• Instructions and training: Issue written instructions on counting, recording, units of measure and the handling of damaged or third-party goods, and brief the teams.
• Arrangement of stock: Put goods in their correct locations, stack them so they can be counted easily, label locations and items, and move goods out of aisles.
• Separation of goods: Set apart damaged, obsolete and returned goods, goods held for others and goods received but not yet recorded.
• Updating records: Post all receipts and issues up to the cut-off so records are current.
• Stationery and equipment: Prepare pre-numbered stock sheets, tags, pens, calculators, weighing scales, measuring tapes, ladders and scanners.
• Control of movement: Arrange for receipts and issues to stop, or to be kept separate and recorded, during the count.

5.1.2 Stock verification

Stock verification is the checking of physical stock against the stock records, carried out by people who are independent of the stores, to confirm that the stock exists, is correctly recorded and is in good condition. While stocktaking is mainly a count done by or for the stores, verification is an independent check of the stores' accountability, usually by internal audit or appointed verification officers.

5.1.2.1 Meaning

Stock verification is the independent physical inspection and counting of stock, item by item or on a sample basis, and the comparison of the results with the bin cards and stores ledger, to confirm the accuracy of the records and the custody of the goods. It also checks that goods are properly stored, that stock levels are reasonable and that there is no obsolete or surplus stock. For example, an internal auditor of a Kenyan food processing company may visit its raw materials warehouse unannounced and verify the quantities of sugar, flour and packaging materials against the records.

5.1.2.2 Reasons for verifying stock

• To confirm the accuracy of stock records: Recorded balances are compared with what is physically there.
• To detect and prevent theft and fraud: Independent checks expose losses and discourage dishonesty by stores staff.
• To confirm the honesty and efficiency of storekeepers: Verification shows whether custodians are accounting properly for the goods in their care.
• To check the condition of stock: Damaged, deteriorated, expired or obsolete items are found and reported.
• To check compliance with procedures: Verifiers confirm that receipts and issues are supported by authorised documents.
• To identify surplus and slow-moving stock: Excess stock tying up money and space is reported for action.
• To support audit and financial reporting: Verified stock figures give assurance to management and external auditors.

5.1.2.3 Methods of stock verification

• Periodic verification: All stock is verified at set times, such as at the year end, usually together with the annual stock take.
• Continuous verification: Verification officers check a few items every day or week so that all items are verified during the year.
• Surprise (spot) verification: Items are checked without notice, which is effective in discovering theft and concealment.
• Sample verification: A random or selected sample of items is verified and the results are used to judge the accuracy of the whole store.
• Selective (ABC-based) verification: High-value A items are verified often and fully, and low-value C items less often or by sampling.
• Verification by reconciliation: Records are traced from documents to bin cards and ledger and then to physical stock, and from physical stock back to records.

5.1.2.4 Stock discrepancies

A stock discrepancy is a difference between the quantity of stock physically found and the quantity shown in the records. A surplus exists when physical stock is more than the record; a deficiency (shortage) exists when it is less. Every discrepancy must be investigated, explained and corrected with authority.

Causes of stock discrepancies:

• Recording errors: Receipts or issues not posted, posted twice or posted to the wrong item.
• Errors at receipt or issue: Wrong quantities counted on receiving or issuing goods.
• Theft and pilferage: Goods removed without authority.
• Breakage, evaporation and deterioration: Natural losses and damage not recorded.
• Units of measure: Goods received in one unit (cartons) and issued in another (pieces) without correct conversion.
• Wrong locations: Goods stored in a different place and missed during the count.
• Counting errors: Mistakes during the stock take itself.

Treatment of discrepancies:

1. Recount the items with differences to confirm the discrepancy.
2. Check documents for unposted, misposted or missing transactions and correct genuine recording errors.
3. Investigate remaining differences to find their cause and the person responsible.
4. Prepare a discrepancy report with the quantities, values, causes and recommended action.
5. Obtain authority from the appropriate officer to write off deficiencies or take surpluses into stock.
6. Post the approved adjustments to the records and take action to prevent recurrence, such as improving security or procedures.

Example: valuing stock discrepancies

A stock verification at the warehouse of a Kenyan paint distributor gives these results:

Emulsion paint: 146 − 150 = −4 tins (deficiency)

Value = 4 × 4,500 = Ksh 18,000 deficiency

Gloss paint: 324 − 320 = +4 tins (surplus)

Value = 4 × 1,200 = Ksh 4,800 surplus

Paint brushes: 470 − 500 = −30 pieces (deficiency)

Value = 30 × 150 = Ksh 4,500 deficiency

Net discrepancy = −18,000 + 4,800 − 4,500 = −Ksh 17,700, a net deficiency of Ksh 17,700

Each item is investigated separately: the surplus on gloss paint does not cancel the shortage on emulsion paint, because they are different items.

Chapter Summary

This chapter focused on maintaining optimum stock levels, beginning with the concept of stock taking, which involves systematically counting and recording inventory to ensure accuracy. The process of stock taking was detailed alongside its importance in preventing losses and ensuring reliable stock records, while also discussing its advantages and disadvantages, various approaches, and the necessary preparation involved. Stock verification was explained as a critical activity to confirm stock accuracy, including the reasons for verification, different methods, and how to handle stock discrepancies. Demand forecasting was defined and highlighted as essential for anticipating future stock needs, with an exploration of several forecasting methods such as time series analysis, the Delphi method, causal models like regression analysis, market research techniques, sales force composite, and lead demand forecasting, as well as challenges faced in this area. The chapter concluded with an examination of stock levels, clarifying their meaning and describing key types such as maximum, minimum, reorder, average, and danger levels, along with the factors that should be considered when setting these levels to ensure efficient inventory management.