5.1.4 Estimation Techniques Flashcards
Test effort estimation involves predicting the amount of test-related work needed to meet the t… of a t…
test objectives
test project.
It’s important to make it clear to the stakeholders that the estimate is based on a n… and is always s…
number of assumptions
subject to estimation error.
Estimation for small tasks is usually more accurate than for the l…
large ones.
Therefore, when estimating for a larger task, it can be decomposed into a s… which then in turn can be “ “.
set of smaller tasks
estimated
Estimation based on ratios
In this metrics-based technique, figures are collected from p… within the “ “ , which makes it possible to derive “s… for s…
previous projects
organization
“standard” ratios
similar projects.
Estimation based on ratios
The ratios of an organization’s own projects (e.g. taken from historical data) are generally the best “ “ to use in the e…
source
estimation process.
Estimation based on ratios
These standard ratios can then be used to estimate the t… for the n…
test effort
new project.
Estimation based on ratios
Example: if in the previous project the development-to-test ratio was 3:2 and in the current project the development effort is expected to be 600 person-days, the t… can be estimated to be 4…
test effort
400 person-days.
Extrapolation
In this metrics-based technique, measurements are made as early as possible in the c… to gather the “ “.
current project
data
Extrapolation
Having enough observations, the effort required for the remaining work can be approximated by e… (usually by applying a m… ).
extrapolating this data
mathematical model
Extrapolation
This method is very suitable in i…
Example: the team may extrapolate the test effort in the forthcoming iteration as the a… from the l…
iterative SDLCs.
averaged effort
last three iterations.
Wideband Delphi
In this iterative, expert-based technique, experts make e…
experience-based estimations.
Wideband Delphi
Each expert, in isolation, e…
estimates the effort.
Wideband Delphi
The results are collected and if there are deviations of an expert’s estimate that are out of range of the agreed upon boundaries, the “ “ discuss their c…
experts
current estimates.
Wideband Delphi
Each expert is then asked to make a n… based on that “ “, again in “ “.
The process is repeated until a c…
new estimation
feedback
isolation
consensus is reached.
Wideband Delphi
Planning Poker is a variant of W… , commonly used in A…
Wideband Delphi
Agile software development.
Wideband Delphi
In Planning Poker, estimates are usually made using cards with “ “ that represent the e…
numbers
effort size.
Three-point estimation
In this expert-based technique, three estimations are made by the experts:
- the most o…
- the most l…
- the most p…
- optimistic estimation (a)
- likely estimation (m)
- pessimistic estimation (b).
Three-point estimation
The final estimate (E) is their w…
weighted arithmetic mean.
Three-point estimation
In the most popular version of this technique, the estimate is calculated as E…
E = (a + 4*m + b) / 6
Three-point estimation
The advantage of this technique is that it allows the experts to calculate the measurement error: S…
SD = (b - a) / 6.
Three-point estimation
Example: if the estimates (in person-hours) are: a=6, m=9, and b=18, then the final estimation is 1… because E = … and SD = …
10+_ 2 person-hours (i.e. between 8 and 12 person-hours)
(6 + 4*9 + 18) / 6 =10
(18 - 6) / 6 =2
