Measurements, estimation and data analysis Flashcards
give me 5 points of Strategic( Organisational Level) Long term
-reducing costs
– expanding customer base
– increasing user satisfaction
– improving productivity
– reducing time-to-market
Give me 2 points of Tactical (Project Level) Medium term
Quality, Time, Cost, Productivity
– Process varies from project to project - compare:
* RAD* of low-cost single-user desktop tool
* enterprise-wide IS project
what is Operational: activity level (short term)
Day-to-day, week-to-week activities which vary greatly depending on the project’s process
what is the purpose of measurement estimation and data analysis
To support reliable Quantitative comparisons evaluations, predictions and decision making relevant to software projects and their artifacts
What is a measurement
Measurement is the process of assigning a value to some attribute of entity, where the value is obtained on a particular scale.
What is a measurement instrument
Something we use to measure
What to measure? Product
Product
– Specifications, designs, test plans, modules, programs…
What to measure? Process
- Process
– Change control, design, project scheduling, review…
What to measure? Resource
Personnel, Money, hardware and Software
Attributes that are difficult to measure
Complexity, Productivity and Quality, length of time before program stops, the halting program
What is a Unit?
A measurement is a scalar Quantity, defined and adopted by convention, with which any other quantity of the same kind can be compared to express the ratio of the two quantities as a number.
how can software size be measured?
Characters,Bytes,Modules, classes and SLOC(Source Lines of Code)
What is Direct Measurement
An attribute that can be measured without the need to measure another attribute. e.g.
Length of source code
Duration of testing process
Number of defects discovered
What is Indirect Measurement
something you cant directly measure but can calculate from other measurements.
Length of a project, Length of development+length of testing
Developer-Days (Num of developrs* num of days)
Programmer productivity(SLOC/Timespent)
What makes a measurement valid?
– accurate – measures the true value of the attribute
– reliable – repeated measurements give similar values
– meaningful – the measurement answers a question that we want answered
Measurement validity
What makes a measurement accurate
Accuracy is important, but needs to be tempered by context
- Acceptability of accuracy varies
– If we’re measuring file size, we expect 100% accuracy
– If we’re measuring number of defects, perhaps ± 10% - Timeliness is more important
– An approximate number of defects tells us whether the software is ready to ship
– A precise number of defects doesn’t add value, but may take time to determine (and can never
be guaranteed as accurate)
Measurement accuracy
Why do we put data onto a scale?
We need to put data onto a scale to see how it compares to anoher piece of Data
What are the 5 types of scales
-Nominal
– Ordinal
– Interval
– Ratio
– Absolute
* Data on a different scale conveys a different level of precision
Scale types
Define Nominal
All we can do with the data is categories it
All we can say s if they are in the same category or not
Define Ordinal
you can categorise them and rank them, but we dont have any indication of the gap between them
Define Interval
We can categorise and rank and has equal intervals, but there is no Zero point, so we cannot make claims that x is twice and big than y
Define Ratio
Can categorise, rank and has equal intervals, but there can be a 0 point
you can say twice as big
Define Absolute, subset of ratio
Cannot determine indirectly frm other measurement, used for counting things. e.g. Number of defects detected by a certain test method, number of lines of code, reused from a previous project, cannot be changed in any way.
Admissible transformations
Can we take data from a scale and transform it, to the same data on another scale
What is Spoilage? and what scale type is it?
SP =
Time to fix post-release defects/
Total development time
Ratio a value of Zero would mean no time fixing post release defects.
What might an atypically large value for SP mean?
Unusually large amount of time on fixing defects, unusually small
amount of time on development, or both
What is estimation:
Estimation is the process of predicting a expected value for some attribute, (whos value is not known)
What is top down?
estimate an overall value and then proportionately distribute this over the components
When is Top down appropriate?
When the project completion time is fixed
What is bottom up?
Estimate a value for individual component and then obtain the overall figure.
When is bottom up appropriate?
For an open ended research project
