Entering Seasonality

This article explains how to enter seasonality in Model Reef input fields.

You will learn:

• What seasonality represents in the model.

• How to input seasonal patterns as multipliers or absolute values.

• How seasonality interacts with base values, schedules and delays.

Seasonality is used to reflect consistent patterns over each year, such as busy and quiet periods.

1. What seasonality means

Seasonality typically captures:

• Higher sales in certain months or quarters.

• Lower activity in off-peak periods.

• Repeating patterns year after year.

Rather than modelling each period independently, you define a pattern that repeats across years unless changed.

2. Ways to enter seasonality

You can usually enter seasonality as:

• Multipliers — percentages or factors that adjust a base value up or down by month.

• Patterned time series — explicit monthly values that repeat on a yearly cycle.

Examples of multipliers:

• January: 0.8

• February: 0.9

• March: 1.1

• Peak months: 1.3

The engine applies these to the underlying base series for the variable or driver.

3. Combining seasonality with base drivers

A common pattern is:

• Set a base annual or monthly value using a driver or formula.

• Apply seasonal multipliers to spread that base across months.

For example:

• Annual forecast revenue for a product.

• Seasonal multipliers allocate more of that revenue into peak months.

This keeps total volume consistent while shaping the intra-year profile.

4. Seasonality and schedules

Seasonality can work alongside schedules:

• A schedule defines when events are allowed or expected to occur.

• Seasonality modifies the magnitude of those events by period.

For instance:

• A monthly schedule for revenue recognition.

• A seasonal pattern that increases volumes in months with predictable spikes.

The combination allows detailed timing and pattern modelling without writing custom formulas for every month.

5. Editing and updating seasonality

1

Open the variable or driver

Open the relevant variable or driver in the model editor.

2

Access the seasonality controls

Access the seasonality section (often via the Timing modal or a dedicated panel).

3

Adjust multipliers or explicit values

Update multipliers or explicit monthly pattern values as needed.

4

Review the resulting series

Review the resulting series or preview chart to confirm the changes.

You can revise seasonality as you learn more about actual behaviour, without rebuilding the underlying variable logic.

6. Validating seasonal assumptions

After setting seasonality:

• Visually inspect the time series to confirm peaks and troughs match expectations.

• Check that annual totals still match high-level targets if you intended them to.

• Compare against historical actuals where available for sanity checks.

Correctly capturing seasonality improves both accuracy and credibility of the model.

Related articles

• Entering Accruals & Delays

• Seasonality Inputs

• Aggregate Categories

• Build a Seasonality Adjusted Forecast