<?xml version="1.0" encoding="utf-8"?>
<ManualTopic ID="/baanerp/cp/onlinemanual/000112" xml:lang="en">
	<Header>
		<Title xmlns:ssa="http://www.ssaglobal.com" xmlns:HTML="http://www.w3.org/TR/REC-html40">Forecast method: time-series analysis</Title>
		<Keyword><Level1>Forecasting method: time-series analysis</Level1>
		</Keyword>
		<Keyword><Level1>Time-series analysis</Level1>
		</Keyword>
	</Header>
	<GeneralSection><Paragraph>SSA ERP calculates the demand forecast according to the <GUIRef href="/baanerp/cp/domains/rpd.fcmd#tsa" role="enum">Time Series Analysis</GUIRef> forecast method based on the average demand and any earlier defined trend influence and seasonal influence.</Paragraph>
		<Paragraph>The demand forecast is computed as follows:</Paragraph>
		<Paragraph>Without trend influence:</Paragraph>
		<Formula><Paragraph UserLevel="Novice" UserType="Taskuser">TD(t) = AV</Paragraph>
		</Formula>
		<Paragraph>With a linear trend influence:</Paragraph>
		<Formula><Paragraph UserLevel="Novice" UserType="Taskuser">TD(t) = CS + TF * t</Paragraph>
		</Formula>
		<Paragraph>With a progressive trend influence:</Paragraph>
		<Formula><Paragraph UserLevel="Novice" UserType="Taskuser">TD(t) = BS * TF ^ (t-1)</Paragraph>
		</Formula>
		<Paragraph>With a constant seasonal influence:</Paragraph>
		<Formula><Paragraph UserLevel="Novice" UserType="Taskuser">FD(t) = TD(t) + SF(t)</Paragraph>
		</Formula>
		<Paragraph>With a progressive seasonal influence:</Paragraph>
		<Formula><Paragraph UserLevel="Novice" UserType="Taskuser">FD(t) = TD(t) * SF(t)</Paragraph>
		</Formula>
		<Paragraph>Where:</Paragraph>
		<TABLE border="1"><TBODY><TR><TD width="16">AV</TD>
					<TD width="305">average demand (*)</TD>
				</TR>
				<TR><TD width="16">CS</TD>
					<TD width="305">constant demand</TD>
				</TR>
				<TR><TD width="16">BS</TD>
					<TD width="305">base demand (the estimated demand for period 1)</TD>
				</TR>
				<TR><TD width="16">TF</TD>
					<TD width="305">trend factor</TD>
				</TR>
				<TR><TD width="16">SF(t)</TD>
					<TD width="305">seasonal factor for period t</TD>
				</TR>
				<TR><TD width="16">TD(t)</TD>
					<TD width="305">trend based demand for period t</TD>
				</TR>
				<TR><TD width="16">FD(t)</TD>
					<TD width="305">demand forecast for period t</TD>
				</TR>
			</TBODY>
		</TABLE>
		<Paragraph>(*) The average demand is the sum of the historical demand figures by period, divided by the number of periods with demand history.</Paragraph>
	</GeneralSection>
	<RelatedTopics><SectionTitle>Related topics</SectionTitle>
		<RelTopic><Link href="/baanerp/cp/onlinemanual/000079" role="manual">Algorithm for demand forecasting</Link>
		</RelTopic>
		<RelTopic><Link href="/baanerp/cp/onlinemanual/000321" role="manual">Forecasting methods</Link>
		</RelTopic>
	</RelatedTopics>
</ManualTopic>
