Seasonality (Seasonal Indexing)

Seasonal indexing is the process of calculating the high’s and low’s of each time period into an index. This is done by **finding an average for an entire set of data that includes the same number of matching periods, then dividing the individual period average into that total average**.

## Why do we take seasonality out of the forecast?

In supply chain, the demand – or the sales – of a given product is said to exhibit seasonality when **the underlying time-series undergoes a predictable cyclic variation depending on the time within the year**. Seasonality is one of most frequently used statistical patterns to improve the accuracy of demand forecasts.

## How do you use seasonal indices?

- Pick time period (number of years)
- Pick season period (month, quarter)
- Calculate average price for season.
- Calculate average price over time.
- Divide season average by over time average price x 100.

### What do seasonal indices tell us?

Seasonal indices tell us **how a particular season compares to the average season**. For example: SI = 1.3 means that season is 1.3 times the average season (that is, the figures for this season are 30% above the seasonal average). It is a peak or high season.

### What is the difference between seasonal factors and seasonal indices?

A seasonal relative (also known as a seasonal index or seasonal factor) is how much the demand for that particular period tends to be above (or below) **the average demand**. … An value of 1.00 means that the demand for that period is exactly the same as the average.

### What are the examples of seasonality?

A market characteristic in which a product or service becomes very popular for a period of a few months each year and then drops off considerably. An example of seasonality would be **Valentine’s Day candy, swimming suits, summer clothes, or Halloween costumes**. Variation with the seasons.

### Which index is used for the measurement of seasonal variation?

Calculation. Seasonal variation is measured in terms of an index, called **a seasonal index**. It is an average that can be used to compare an actual observation relative to what it would be if there were no seasonal variation.

### How do you interpret seasonality index?

If the seasonal index for summer was 1.5, then that means Christopher earns 50% more than the average $100,000. Likewise a seasonal index of 0.6 in winter would indicate that Christopher earns 40% less than the seasonal average.

### What methods are commonly used for forecasting?

**Quantitative Forecasting Methods**

- Straight Line. A straight-line forecasting method is one of the easiest to implement, requiring only basic math and providing reasonable estimates for what businesses can anticipate in future financial scenarios. …
- Moving Average. …
- Time Series. …
- Linear Regression. …
- Market Research. …
- Delphi Method.

### What does an Arima model do?

Autoregressive integrated moving average (ARIMA) models **predict future values based on past values**. ARIMA makes use of lagged moving averages to smooth time series data. They are widely used in technical analysis to forecast future security prices.

### How does seasonality affect tourism?

Seasonality **causes the fluctuation in tourists and visitor numbers to a destination**. Therefore, some destinations at certain times have more tourists and visitors than they are able to accommodate, while at other times, there are too few tourists and visitors to the region.

### What is the significance of seasonal patterns?

A lot of data is affected by the time of the year, and adjusting for the seasonality means that **more accurate relative comparisons can be drawn between different time periods**. Adjusting data for seasonality evens out periodic swings in statistics or movements in supply and demand related to changing seasons.

### What do the seasonal indices add up to when using quarterly data?

The sum of all indices should be **100%*(number of seasons)**. In case you have lost some precision during the calculation, you may need to normalize your data. For quarters, divide 400% by your sum, then multiply each index by the obtained coefficient. After that, they will add up to 400%.

### What is seasonal analysis with an example?

Answer: Seasonality refers to predictable changes that occur over a one-year period in a business or economy based on the seasons including calendar or commercial seasons. … One example of a seasonal measure is **retail sales**, which typically sees higher spending during the fourth quarter of the calendar year.

### How seasonality can affect inventory?

Seasonal inventory **may result in over-ordering of stock**, and if supply drops sooner than expected, you may be left with an excess amount of stock. … Relatedly, seasonal inventory means increased costs to your business, since you will often have to stock up on the inventory well in advance of the surge in demand.

### What are the seasonal products?

Products that are either **not available** on the market during certain seasons or periods of the year or are available throughout the year but with regular fluctuations in their quantities and prices that are linked to the season or time of the year.

### How do you do seasonal index in Excel?

Enter the following formula into cell C2: **“=B2 / B$15”** omitting the quotation marks. This will divide the actual sales value by the average sales value, giving a seasonal index value.

### How do seasons affect businesses?

Seasonality plays an important role in business. Oftentimes, it is the cause of otherwise unexplained increases and decreases in sales. Those who lack an understanding of an industry’s natural cycle might misdiagnose a decline in sales, especially if it lasts longer than two months.

### What is the approximate seasonal index for July?

The three previous July values were 110, 150, and 130. The average over all the 36 months from the three years is 190. The approximate seasonal index for July is: **2.053 0.384 0.684 0.287**.

### How do you forecast seasonal demand?

**How to forecast for seasonal demand**

- Identify which products are affected by seasonal demand. …
- Understand when the peaks will happen. …
- Accurately forecast the relative size of those peaks compared to normal demand. …
- Understand the level of uncertainty associated with those forecasted peaks.

### What does a seasonal factor mean?

A seasonal factor **measures the percentage amount**. **that on average, a month is above or below normal**. A seasonal factor of 120 states that the month in. question will usually be 20% above an average. month’s level.

### How do you create a seasonal index?

The seasonal index of each value is calculated by **dividing the period amount by the average of all periods**. This creates a relationship between the period amount and the average that reflects how much a period is higher or lower than the average. =Period Amount / Average Amount or, for example, =B2/$B$15.