Estimation Techniques - Revision history

S184314 at 21:48, 9 May 2023

2023-05-09T21:48:59Z

← Older revision		Revision as of 21:48, 9 May 2023
Line 79:		Line 79:
	====Analogous Estimating====		====Analogous Estimating====

	[[File:Analogous.png\|~~500px~~\|thumb\|right\|Figure 3: Analogous estimating <ref name="nine"/>]]		[[File:Analogous.png\|400px\|thumb\|right\|Figure 3: Analogous estimating <ref name="nine"/>]]

	Analogous estimating is a top-down project management estimation technique that uses historical data or expert judgment <ref name="nine"/> to estimate the parameters of a new project <ref name="six"/>. It is a top-down approach to estimating, as it looks at the overall project first <ref name="nine"/>. Furthermore, it relies on the assumption that the current project is similar in scope, complexity, and requirements to past projects, and that historical data can be used to derive estimates for the current project. An example of analogous estimating might involve estimating the cost of a new construction project based on the cost of a similar construction project completed in the past. The historical data would be used to identify the key cost drivers of the previous project, and these drivers would be applied to the current project to derive an estimate of its cost.		Analogous estimating is a top-down project management estimation technique that uses historical data or expert judgment <ref name="nine"/> to estimate the parameters of a new project <ref name="six"/>. It is a top-down approach to estimating, as it looks at the overall project first <ref name="nine"/>. Furthermore, it relies on the assumption that the current project is similar in scope, complexity, and requirements to past projects, and that historical data can be used to derive estimates for the current project. An example of analogous estimating might involve estimating the cost of a new construction project based on the cost of a similar construction project completed in the past. The historical data would be used to identify the key cost drivers of the previous project, and these drivers would be applied to the current project to derive an estimate of its cost.
Line 101:		Line 101:
	====Three-point Estimation====		====Three-point Estimation====

	[[File:TP.png\|~~500px~~\|thumb\|right\|Figure 4: Distribution of the Three point estimate <ref name="eleven"/>]]		[[File:TP.png\|400px\|thumb\|right\|Figure 4: Distribution of the Three point estimate <ref name="eleven"/>]]
	Known from the iron law of mega projects<ref name="five"/> the larger a project the more likely it is to exceed budget, schedule and quality. From the iron law of mega projects Bent Flyvbjerg mentions ''“Nine out of ten such projects have cost overruns. Overruns of up to 50 percent in real terms are common, over 50 percent not uncommon”''<ref name="five"/>. This is where three point estimating comes into the picture trying to prevent overruns from happening by estimating the duration or cost of a project or a task using three estimates: an optimistic estimate, a pessimistic estimate, and a most likely estimate. Thereby this estimation technique also includes the possibility of the project being over time, budget or quality. Even though this technique includes the pessimistic scenario it also includes an optimistic scenario which could balance the calculation to be closer to the anticipated most likely scenario <ref name="seven"/>. This technique is mainly used after performing an estimate using one of the mentioned estimation techniques in this article.		Known from the iron law of mega projects<ref name="five"/> the larger a project the more likely it is to exceed budget, schedule and quality. From the iron law of mega projects Bent Flyvbjerg mentions ''“Nine out of ten such projects have cost overruns. Overruns of up to 50 percent in real terms are common, over 50 percent not uncommon”''<ref name="five"/>. This is where three point estimating comes into the picture trying to prevent overruns from happening by estimating the duration or cost of a project or a task using three estimates: an optimistic estimate, a pessimistic estimate, and a most likely estimate. Thereby this estimation technique also includes the possibility of the project being over time, budget or quality. Even though this technique includes the pessimistic scenario it also includes an optimistic scenario which could balance the calculation to be closer to the anticipated most likely scenario <ref name="seven"/>. This technique is mainly used after performing an estimate using one of the mentioned estimation techniques in this article.

Line 192:		Line 192:


	[[File:comparison.PNG\|~~500px~~\|thumb\|right\|Figure 5: Quick overview of estimation techniques <ref name="eight"/>]]		[[File:comparison.PNG\|400px\|thumb\|right\|Figure 5: Quick overview of estimation techniques <ref name="eight"/>]]

	In summary, each estimation technique has its own advantages and disadvantages, but it can be challenging to determine the most efficient way to use them. It is important to note that each project is unique and there is no one-size-fits-all approach to estimating costs or durations. However, a best practice is to identify the project's scope and timeframe to decide between a top-down or ground-up approach. For example, a ground-up approach may be preferable for projects with a long time horizon, while a top-down approach may be more beneficial for projects with a tight timeline. Additionally, the amount of available information plays a significant role in selecting the appropriate estimation technique.		In summary, each estimation technique has its own advantages and disadvantages, but it can be challenging to determine the most efficient way to use them. It is important to note that each project is unique and there is no one-size-fits-all approach to estimating costs or durations. However, a best practice is to identify the project's scope and timeframe to decide between a top-down or ground-up approach. For example, a ground-up approach may be preferable for projects with a long time horizon, while a top-down approach may be more beneficial for projects with a tight timeline. Additionally, the amount of available information plays a significant role in selecting the appropriate estimation technique.

S184314 at 21:48, 9 May 2023

2023-05-09T21:48:27Z

← Older revision		Revision as of 21:48, 9 May 2023
Line 11:		Line 11:
	== Introduction to estimation techniques ==		== Introduction to estimation techniques ==

	[[File:TopDownGroundUp.png\|~~500px~~\|thumb\|right\|Figure 1: Top-down and Ground-up approach <ref name="twelve"/>]]		[[File:TopDownGroundUp.png\|400px\|thumb\|right\|Figure 1: Top-down and Ground-up approach <ref name="twelve"/>]]

	The big idea behind this article is to investigate top-down and ground-up estimations as they are the two most different approaches to estimate the size, scope, and cost or time of a project or initiative. Understanding the essentials of this theory will then aid in understanding and applying other techniques that share similarities with top-down and ground-up estimations.		The big idea behind this article is to investigate top-down and ground-up estimations as they are the two most different approaches to estimate the size, scope, and cost or time of a project or initiative. Understanding the essentials of this theory will then aid in understanding and applying other techniques that share similarities with top-down and ground-up estimations.
Line 41:		Line 41:
	Ground-up estimating or bottom-up estimating is a project estimation technique that involves breaking down the project into smaller, more manageable components, and estimating the effort, duration, or cost required for each of these components individually. These estimates are then aggregated to arrive at an overall estimate for the project <ref name="seven"/>. An example of applying ground-up estimating could involve estimating the effort required to develop a new software application. The project could be broken down into smaller tasks, such as designing the user interface, coding the application, testing the application, and deploying the application. The effort required for each task would then be estimated individually, and the estimates would be aggregated to arrive at an overall estimate for the project. Based on the level of detail ground-up estimating is more accurate than top-down estimating because it provides a detailed breakdown of the project cost or duration. This makes it easier to identify specific areas where costs or timelines may need to be adjusted. Ground-up estimating is often used in later stages of a project when the level of detail required for a ground-up estimate is available.		Ground-up estimating or bottom-up estimating is a project estimation technique that involves breaking down the project into smaller, more manageable components, and estimating the effort, duration, or cost required for each of these components individually. These estimates are then aggregated to arrive at an overall estimate for the project <ref name="seven"/>. An example of applying ground-up estimating could involve estimating the effort required to develop a new software application. The project could be broken down into smaller tasks, such as designing the user interface, coding the application, testing the application, and deploying the application. The effort required for each task would then be estimated individually, and the estimates would be aggregated to arrive at an overall estimate for the project. Based on the level of detail ground-up estimating is more accurate than top-down estimating because it provides a detailed breakdown of the project cost or duration. This makes it easier to identify specific areas where costs or timelines may need to be adjusted. Ground-up estimating is often used in later stages of a project when the level of detail required for a ground-up estimate is available.

	[[File:groundup.png\|~~500px~~\|thumb\|right\|Figure 2: Ground-up level durations <ref name="three"/>]]		[[File:groundup.png\|400px\|thumb\|right\|Figure 2: Ground-up level durations <ref name="three"/>]]

S184314: /* Comparison of estimation techniques */

2023-05-09T21:46:00Z

Comparison of estimation techniques

← Older revision		Revision as of 21:46, 9 May 2023
Line 146:		Line 146:
	To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.		To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.

	\| class="wikitable" style="background-color:#ffffff;"		{\| class="wikitable" style="background-color:#ffffff;"
	\|- style="font-weight:bold; text-align:center;"		\|- style="font-weight:bold; text-align:center;"
	! style="font-weight:normal;" \|		! style="font-weight:normal;" \|

S184314: /* Comparison of estimation techniques */

2023-05-09T21:45:21Z

Comparison of estimation techniques

S184314: /* Introduction to estimation techniques */

2023-05-09T20:21:55Z

Introduction to estimation techniques

← Older revision		Revision as of 20:21, 9 May 2023
Line 21:		Line 21:
	Top-down estimating is a project management technique that involves estimating the total cost or duration of a project without using detailed information or analysis. It starts with evaluating a projects budget, duration or scope as a whole and then separating it into smaller components<ref name="seven"/>. It is often used by company leadership and project managers. Used techniques often include estimation from experienced estimators and historical data from similar projects to make an educated guess of the overall cost or duration of the project <ref name="three"/>. The estimate is based on the information available at the start of the project, hence the tasks in the work breakdown structure (WBS) are not clearly defined yet. In top-down estimations, the first step is for the project manager to identify the major deliverables or expenses that are required to complete the project. Then, using their experience or historical data, they estimate the total cost or duration of the project. The experienced estimators can be internally in the form of experienced managers and sometimes externally as outside experts. The top-down estimation priorities efficiency as it does not need middle management <ref name="one"/> to provide detailed cost break downs, which allows managers to quickly asses potential opportunities, costs and durations. It can also be used for projects with a high degree of uncertainty or when a limited amount of information available.		Top-down estimating is a project management technique that involves estimating the total cost or duration of a project without using detailed information or analysis. It starts with evaluating a projects budget, duration or scope as a whole and then separating it into smaller components<ref name="seven"/>. It is often used by company leadership and project managers. Used techniques often include estimation from experienced estimators and historical data from similar projects to make an educated guess of the overall cost or duration of the project <ref name="three"/>. The estimate is based on the information available at the start of the project, hence the tasks in the work breakdown structure (WBS) are not clearly defined yet. In top-down estimations, the first step is for the project manager to identify the major deliverables or expenses that are required to complete the project. Then, using their experience or historical data, they estimate the total cost or duration of the project. The experienced estimators can be internally in the form of experienced managers and sometimes externally as outside experts. The top-down estimation priorities efficiency as it does not need middle management <ref name="one"/> to provide detailed cost break downs, which allows managers to quickly asses potential opportunities, costs and durations. It can also be used for projects with a high degree of uncertainty or when a limited amount of information available.

	~~some~~ advantages for top-down estimating are:		Some advantages for top-down estimating are:
	* Can be used with limited amount of available information.		* Can be used with limited amount of available information.

Line 29:		Line 29:


	~~some~~ disadvantages for top-down estimating are:		Some disadvantages for top-down estimating are:

	*Top-down estimating lacks detail and is less accurate than ground-up.		*Top-down estimating lacks detail and is less accurate than ground-up.

S184314: /* Comparison of estimation techniques */

2023-05-09T20:18:39Z

Comparison of estimation techniques

← Older revision		Revision as of 20:18, 9 May 2023
Line 149:		Line 149:
	\|- style="font-weight:bold; text-align:center;"		\|- style="font-weight:bold; text-align:center;"
	! style="font-weight:normal;" \|		! style="font-weight:normal;" \|
	! style="~~text~~-~~align~~:~~left~~;" \| Top-Down Estimating		! style="background-color:#efefef;" \| Top-Down Estimating
	! style="background-color:#efefef;" \| Expert Judgement		! style="background-color:#efefef;" \| Expert Judgement
	! style="background-color:#efefef;" \| Analogous Estimating		! style="background-color:#efefef;" \| Analogous Estimating
	! Parametric Estimating<br />		! style="background-color:#efefef;" \| Parametric Estimating<br />
	! style="background-color:#efefef;" \| Three-Point Estimating		! style="background-color:#efefef;" \| Three-Point Estimating
	! style="background-color:#efefef; color:#000000;" \| Bottom-up Estimating		! style="background-color:#efefef; color:#000000;" \| Bottom-up Estimating

S184314: /* Estimation techniques and their application */

2023-05-09T20:16:17Z

Estimation techniques and their application

← Older revision		Revision as of 20:16, 9 May 2023
Line 64:		Line 64:
	==Estimation techniques and their application==		==Estimation techniques and their application==

	In summary top-down is a high-level approach that is used when limited information is available whereas ground-up is a detailed approach where estimating the cost or duration of each work package at the lowest possible level, and then aggregating the estimates to produce a total cost or duration for the project. These approaches ~~cannot independently~~ find a sufficient or accurate ~~estimate~~ and multiple methods therefore exist in order to help estimations become as accurate as possible. Whereas, some methods share similarities with top-down estimating and other ground-up estimating some can be applied at both levels.		In summary top-down is a high-level approach that is used when limited information is available whereas ground-up is a detailed approach where estimating the cost or duration of each work package at the lowest possible level, and then aggregating the estimates to produce a total cost or duration for the project. These approaches do not alone find a sufficient or accurate estimates and multiple methods therefore exist in order to help estimations become as accurate as possible. Whereas, some methods share similarities with top-down estimating and other ground-up estimating some can be applied at both levels.

	====Expert Judgement====		====Expert Judgement====

S184314: /* Comparison of estimation techniques */

2023-05-09T20:12:00Z

Comparison of estimation techniques

← Older revision		Revision as of 20:12, 9 May 2023
Line 145:		Line 145:

	To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.		To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.





	{\| class="wikitable"		{\| class="wikitable"

S184314: /* Comparison of estimation techniques */

2023-05-09T20:11:51Z

Comparison of estimation techniques

← Older revision		Revision as of 20:11, 9 May 2023
Line 147:		Line 147:


	~~{\| class="wikitable"~~
	~~\|- style="font-weight:bold;"~~
	~~! style="font-weight:normal;" \| <br />~~
	~~! <br />Analogous Estimating~~
	~~! <br />Bottom-up Estimating~~
	~~! <br />Parametric Estimating~~
	~~! <br />Expert Judgment<br />~~
	~~! <br />Three-Point Estimating~~
	\|-
	~~\| style="font-weight:bold;" \| <br />Input Data <br /><ref name="three"/>, <ref name="four"/><br />~~
	~~\| <br />Data from previous comparable<br />projects~~
	~~\| <br />Activities & their scope of labour from the WBS <br /><br />~~
	~~\| <br />Data from previous comparable<br />projects~~
	~~\| <br />Internal or external professionals' knowledge <br />and experience~~
	~~\| <br />Different techniques for estimating <br />costs~~
	\|-
	~~\| style="font-weight:bold;" \| <br />Method~~
	~~\| Using data of past similar<br />projects & adapting it<br />~~
	~~\| Estimating costs at the lowest <br />possible detail, then aggregating <br />the different components<br />~~
	~~\| Using data of past projects the<br />present project's cost or duration per parameter unit.<br />~~
	~~\| Experts provide estimates of the<br />resources required to perform the<br /> job within the scope of the project, <br />either from the top-down or from <br />the bottom-up.~~
	\| An optimistic, pessimistic, and most<br />likely estimate is by using one of <br />the four other approaches <br />and are then based on the Pert distribution or triangular <br />converted into a weighted average value .
	\|-
	~~\| style="font-weight:bold;" \| <br />Output Type~~
	~~\| <br />Total cost or duration of the project<br /><br />~~
	~~\| <br />Total cost or duration of the project, as well<br />as a cost of each activity~~
	~~\| <br />Total cost or duration of the project, as well<br />as a cost of each activity<br />~~
	~~\| <br />Varies from each project, but <br />often times several outputs~~
	~~\| <br />Final estimates of costs or duration, <br />, standard deviation<br /> of estimates~~
	\|-
	~~\| style="font-weight:bold;" \| Limitations~~
	~~\| Risk of being inaccurate as a result of being a top-down estimations<br />Mostly used in the beginning <br />of a project. Bias can also be a limitation.~~
	~~\| Time consuming and it does not consider the <br />ressources required for<br /> aggregating each activity~~
	~~\| Requires historical data which can be <br />time consuming to gather and may <br />not be available~~
	~~\| Can be expensive if external consultants are hired as well as time consuming. Furthermore, experts can be biased.~~
	~~\| Time consuming to provide an estimate for<br /> all three scenarios. Can be biased when coming up with a most likely, pessimistic and optimistic scenario.~~
	\|}

S184314: /* Top-down estimations */

2023-05-09T20:11:13Z

Top-down estimations

← Older revision		Revision as of 20:11, 9 May 2023
Line 35:		Line 35:
	* Limited to senior managers and stakeholders in the organization		* Limited to senior managers and stakeholders in the organization

	As a result of the inaccuracy associated with top-down estimations, techniques exist to assist in minimizing the error, here among analogous estimating.		As a result of the inaccuracy associated with top-down estimations, techniques exist to assist in minimizing the error, here among analogous estimating and expert judgement.

	====Ground-up estimations====		====Ground-up estimations====

← Older revision		Revision as of 20:18, 9 May 2023
Line 149:		Line 149:
	\|- style="font-weight:bold; text-align:center;"		\|- style="font-weight:bold; text-align:center;"
	! style="font-weight:normal;" \|		! style="font-weight:normal;" \|
	! style="~~text~~-~~align~~:~~left~~;" \| Top-Down Estimating		! style="background-color:#efefef;" \| Top-Down Estimating
	! style="background-color:#efefef;" \| Expert Judgement		! style="background-color:#efefef;" \| Expert Judgement
	! style="background-color:#efefef;" \| Analogous Estimating		! style="background-color:#efefef;" \| Analogous Estimating
	! Parametric Estimating<br />		! style="background-color:#efefef;" \| Parametric Estimating<br />
	! style="background-color:#efefef;" \| Three-Point Estimating		! style="background-color:#efefef;" \| Three-Point Estimating
	! style="background-color:#efefef; color:#000000;" \| Bottom-up Estimating		! style="background-color:#efefef; color:#000000;" \| Bottom-up Estimating

← Older revision		Revision as of 20:11, 9 May 2023
Line 147:		Line 147:


	~~{\| class="wikitable"~~
	~~\|- style="font-weight:bold;"~~
	~~! style="font-weight:normal;" \| <br />~~
	~~! <br />Analogous Estimating~~
	~~! <br />Bottom-up Estimating~~
	~~! <br />Parametric Estimating~~
	~~! <br />Expert Judgment<br />~~
	~~! <br />Three-Point Estimating~~
	\|-
	~~\| style="font-weight:bold;" \| <br />Input Data <br /><ref name="three"/>, <ref name="four"/><br />~~
	~~\| <br />Data from previous comparable<br />projects~~
	~~\| <br />Activities & their scope of labour from the WBS <br /><br />~~
	~~\| <br />Data from previous comparable<br />projects~~
	~~\| <br />Internal or external professionals' knowledge <br />and experience~~
	~~\| <br />Different techniques for estimating <br />costs~~
	\|-
	~~\| style="font-weight:bold;" \| <br />Method~~
	~~\| Using data of past similar<br />projects & adapting it<br />~~
	~~\| Estimating costs at the lowest <br />possible detail, then aggregating <br />the different components<br />~~
	~~\| Using data of past projects the<br />present project's cost or duration per parameter unit.<br />~~
	~~\| Experts provide estimates of the<br />resources required to perform the<br /> job within the scope of the project, <br />either from the top-down or from <br />the bottom-up.~~
	\| An optimistic, pessimistic, and most<br />likely estimate is by using one of <br />the four other approaches <br />and are then based on the Pert distribution or triangular <br />converted into a weighted average value .
	\|-
	~~\| style="font-weight:bold;" \| <br />Output Type~~
	~~\| <br />Total cost or duration of the project<br /><br />~~
	~~\| <br />Total cost or duration of the project, as well<br />as a cost of each activity~~
	~~\| <br />Total cost or duration of the project, as well<br />as a cost of each activity<br />~~
	~~\| <br />Varies from each project, but <br />often times several outputs~~
	~~\| <br />Final estimates of costs or duration, <br />, standard deviation<br /> of estimates~~
	\|-
	~~\| style="font-weight:bold;" \| Limitations~~
	~~\| Risk of being inaccurate as a result of being a top-down estimations<br />Mostly used in the beginning <br />of a project. Bias can also be a limitation.~~
	~~\| Time consuming and it does not consider the <br />ressources required for<br /> aggregating each activity~~
	~~\| Requires historical data which can be <br />time consuming to gather and may <br />not be available~~
	~~\| Can be expensive if external consultants are hired as well as time consuming. Furthermore, experts can be biased.~~
	~~\| Time consuming to provide an estimate for<br /> all three scenarios. Can be biased when coming up with a most likely, pessimistic and optimistic scenario.~~
	\|}

← Older revision		Revision as of 21:45, 9 May 2023
Line 146:		Line 146:
	To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.		To summarize the advantages and limitations of the estimation techniques, a table has been made to create an overview of the differences of the techniques.

	{\| class="wikitable"		\| class="wikitable" style="background-color:#ffffff;"
	\|- style="font-weight:bold; text-align:center;"		\|- style="font-weight:bold; text-align:center;"
	! style="font-weight:normal;" \|		! style="font-weight:normal;" \|
	! ~~style="background-color:#efefef;" \|~~ Top-Down Estimating		! Top-Down <br />Estimating
	! ~~style="background-color:#efefef;" \|~~ Expert Judgement		! Expert <br />Judgement
	! ~~style="background-color:#efefef;" \|~~ Analogous Estimating		! Analogous Estimating
	! ~~style="background-color:#efefef;" \|~~ Parametric Estimating<br />		! Parametric Estimating<br />
	! ~~style="background-color:#efefef;" \|~~ Three-Point Estimating		! Three-Point Estimating
	! style="~~background-color:#efefef;~~ color:#000000;" \| Bottom-up Estimating		! style="color:#000000;" \| Bottom-up Estimating
	\|-		\|-
	\| style="text-align:center; font-weight:bold~~; background-color:#efefef~~;" \| Input Data		\| style="text-align:center; font-weight:bold;" \| Input Data
	\| Internal or external professionals' knowledge<br />and experience.<br /><br />Data from previous comparable projects<br />		\| style="font-size:13px;" \| Internal or external professionals' knowledge<br />and experience.<br /><br />Data from previous comparable projects<br />
	\| Internal or external professionals' knowledge <br />and experience		\| style="font-size:13px;" \| Internal or external professionals' knowledge <br />and experience
	\| Data from previous comparable projects.		\| style="font-size:13px;" \| Data from previous comparable projects.
	\| Data from previous comparable<br />projects.		\| style="font-size:13px;" \| Data from previous comparable<br />projects.
	\| Different techniques for estimating <br />costs		\| style="font-size:13px;" \| Different techniques for estimating <br />costs
	\| Activities & their scope of labour from the WBS		\| style="font-size:13px;" \| Activities & their scope of labour from the WBS
	\|-		\|-
	\| style="text-align:center; font-weight:bold; ~~background~~-~~color~~:~~#efefef~~;" ~~\| Method~~		\| style="text-align:center; font-weight:bold;" \| Method
	\| When at early stage, experts provide estimates<br />of the resources top-down.<br /><br />Using data of past similar projects to <br />give an overall estimate.		\| style="font-size:13px;" \| When at early stage, experts provide estimates<br />of the resources top-down.<br /><br />Using data of past similar projects to <br />give an overall estimate.
	\| Experts provide estimates of the<br />resources required to perform the<br />job within the scope of the project,<br />either from the top-down or from<br />the bottom-up.		\| style="font-size:13px;" \| Experts provide estimates of the<br />resources required to perform the<br />job within the scope of the project,<br />either from the top-down or from<br />the bottom-up.
	\| Using data of past similar<br />projects & adapting it.		\| style="font-size:13px;" \| Using data of past similar<br />projects & adapting it.
	\| Using data of past projects the<br />present project's cost or duration per parameter unit.		\| style="font-size:13px;" \| Using data of past projects the<br />present project's cost or duration per parameter unit.
	\| An optimistic, pessimistic, and most<br />likely estimate is by using one of<br />the four other approaches<br />and are then based on the Pert distribution or triangular<br />converted into a weighted average value.		\| style="font-size:13px;" \| An optimistic, pessimistic, and most<br />likely estimate is by using one of<br />the four other approaches<br />and are then based on the Pert distribution or triangular<br />converted into a weighted average value.
	\| Estimating costs at the lowest<br />possible detail, then aggregating<br />the different components		\| style="font-size:13px;" \| Estimating costs at the lowest<br />possible detail, then aggregating<br />the different components
	\|-		\|-
	\| style="text-align:center; font-weight:bold~~; background-color:#efefef~~;" \| Output Type		\| style="text-align:center; font-weight:bold;" \| Output Type
	\| An overall estimate of the cost or duration.		\| style="font-size:13px;" \| An overall estimate of the cost or duration.
	\| Varies from each project, but<br />often times several outputs.		\| style="font-size:13px;" \| Varies from each project, but<br />often times several outputs.
	\| Total cost or duration of the project.		\| style="font-size:13px;" \| Total cost or duration of the project.
	\| Total cost or duration of the project, as well<br />as a cost of each activity.		\| style="font-size:13px;" \| Total cost or duration of the project, as well<br />as a cost of each activity.
	\| Final estimates of costs or duration, standard deviation<br />of estimates		\| style="font-size:13px;" \| Final estimates of costs or duration, standard deviation<br />of estimates
	\| Total cost or duration of the project, as well<br />as a cost of each activity		\| style="font-size:13px;" \| Total cost or duration of the project, as well<br />as a cost of each activity
	\|-		\|-
	\| style="text-align:center; font-weight:bold; ~~background~~-~~color~~:~~#efefef~~;" ~~\| Limitations~~		\| style="text-align:center; font-weight:bold;" \| Limitations
	\| Lacks detail and can therefore be inaccurate.<br />Can be biased.<br />Limited to senior managers and stakeholders<br />		\| style="font-size:13px;" \| Lacks detail and can therefore be inaccurate.<br />Can be biased.<br />Limited to senior managers and stakeholders<br />
	\| Can be expensive if external consultants are hired <br />as well as time consuming. Furthermore, experts can be biased.		\| style="font-size:13px;" \| Can be expensive if external consultants are hired <br />as well as time consuming. Furthermore, experts can be biased.
	\| Risk of being inaccurate as a result of being a top-down estimations<br />Mostly used in the beginning<br />of a project. Bias can also be a limitation.		\| style="font-size:13px;" \| Risk of being inaccurate as a result of being a top-down estimations<br />Mostly used in the beginning<br />of a project. Bias can also be a limitation.
	\| Requires historical data which can be <br />time consuming to gather and may<br />not be available.		\| style="font-size:13px;" \| Requires historical data which can be <br />time consuming to gather and may<br />not be available.
	\| Time consuming to provide an estimate for<br />all three scenarios. Can be biased when coming up <br />with a most likely, pessimistic and optimistic scenario.		\| style="font-size:13px;" \| Time consuming to provide an estimate for<br />all three scenarios. Can be biased when coming up <br />with a most likely, pessimistic and optimistic scenario.
	\| Time consuming and it does not consider the<br />resources required for aggregating each activity		\| style="font-size:13px;" \| Time consuming and it does not consider the<br />resources required for aggregating each activity
	\|}		\|}