Normative & Descriptive Approaches to Work Analysis

Psych 562 Week 3 DiscussionShane Davis

Work Analysis

• Systematic investigation of work, jobs, and the relationships among jobs

• Three categories– Normative• “What should be”

– Descriptive• “What is”

– Formative• “What could be”

Normative Approach

• How the system “should” behave• Example: Task analysis– Input/Output• “Black box”

– Sequential Flow• Step-by-step

– Timeline• Remember GOMS?

A Real-World Analogy

Input/Output Sequential Flow / Timeline

“What should be done”“What shouldn’t be done”

Inputs:Miles traveled since last fill-up

Gallons at this fill-up

Output:Gas consumption rate (Km/L)

Constraints:1 mile = 1.609 Km

1 gallon = 3.785 Liters

1. Read current odometer value (2 sec)2. Read odometer value at last fill-up (2 sec)3. Calculate difference (5 sec)4. Multiply by 1.609 (5 sec)5. Let this value equal X6. Read gallons at this fill-up (2 sec)7. Multiply by 3.785 (5 sec)8. Let this value equal Y9. Divide X by Y (5 sec)

Task Analysis:Constraints Vs. Instructions

Constraints• Less detailed

– More worker discretion• Health benefits

• Less guidance– Greater risk of error

• Accommodates variability– More learning opportunities

• More device-independent– Fewer assumptions

Instructions• More detailed

– Less worker discretion• Health risks

• More guidance– Lesser risk of error

• Little room for variability– Fewer learning opportunities

• More device-dependent– More assumptions

The Problem With Instruction:The Task-Artifact Cycle

Because instruction-based analyses are relatively device-dependent, any change to the device designs affects workers’

tasks, subsequently necessitating new device designs, etc.

Closed and Open Systems

• Closed system = predictable; isolated from environment– Does a truly closed system actually exist?

• Open system = dynamic; susceptible to environmental disturbances– Context-conditioned variability– Examples?

• Continuum, not a dichotomy– The more open a system is, the less appropriate

instruction-based analyses are

Work Domain Analysis:Shifting Focus from Task to Structure

Task Analysis(Event Dependent)

Work Domain Analysis(Event Independent)

What to Take from Normative Analyses

• Instruction-based analyses, while common, aren’t well-suited for complex open systems

• Constraint-based analyses allow for worker discretion and device independence– Cannot account for novel situations and events• But work domain analysis can

Descriptive Approach

• Normative = “ideal”• Descriptive = “real”– What do workers actually do in practice?• Task vs. activity

– Field studies• Is one of these approaches better?

Why Descriptive?

• Can lead to unique insights• Examine how theory matches up with reality– Context-conditioned variability– Communication and teamwork– Tools and artifacts– History and culture– Expertise

• Normative is not enough

Descriptive is Not Enough

Our observations of real-world practices are device dependent and can lead us to conflate “workaround”

and “functional” actions while overlooking novel possibilities that may address intrinsic constraints.

Descriptive is Not Enough

Techniques such as rapid prototyping can help overcome the limitations of a descriptive approach, but they are still subject to the task-artifact cycle, are bound

by creativity, and cannot predict unique events.

Possible Solution: Modeling

• Model intrinsic work constraints– E.g. Traffic regulations; laws of physics– NOT issues with current design(s)

• Why model?– Synthesize data– Make predictions

• Of course, not always feasible

Summary

• Normative and descriptive approaches are both useful but not independently sufficient

• Work analysis should include:– Constraint-based analyses– Work domain analyses– Expertise, historical/cultural factors, etc.

• By integrating idealistic goals with current practices we can develop formative approaches– Design as an output, not an input

Thank you!

• Questions, comments, etc.