Professor John Canny Fall 2001 Sept 11, 2001 CS 160: Lecture 5 Professor John Canny Fall 2001 Sept 11, 2001 12/8/2018

Administrivia You’re in a project group now (see the web site) Make sure you meet this week and come up with a project proposal. Hand in the proposal by Friday 5pm. Ask the audience what is wrong with this! 12/8/2018

Task Analysis A technique for analyzing existing tasks by observation. Doesn’t require understanding of Users’ goals, just what they do. But because of that its harder to apply to the design of a new system. Good for training materials and documentation Ask the audience what is wrong with this! 12/8/2018

Task Analysis: 3 Approaches Tasks decomposition: looks at how a task is split into subtasks and the order in which these are performed. Knowledge-based techniques: what do users need to know about the objects and actions involved in a task? How is that knowledge organized? Entity-relation-based analysis: an object-based approach, identify objects, relationships and actions. Ask the audience what is wrong with this! 12/8/2018

Task Decomposition Break the task into subtasks: Hierarchical Task Analysis (HTA): Organize tasks into a hierarchy Include ordering constraints Looks something like logic programming (PROLOG) Clean house Ask the audience what is wrong with this! Get vacuum cleaner Clean rooms Empty dustbag Put everything away Clean hall Clean living room Clean bedrooms 12/8/2018

Task Decomposition 0. In order to clean house Get vacuum cleaner out Fix attachment Clean the rooms 3.1 Clean the hall 3.2 Clean the living rooms 3.3 Clean the bedrooms Empty the dustbag Put the vacuum cleaner away Plan 0: Do 1-2-3-5 in that order Plan 3: Do any of 3.1, 3.2, and 3.3 in any order depending on which rooms need cleaning Ask the audience what is wrong with this! 12/8/2018

Task Decomposition Real tasks have more structure: Possible ordering of steps Frequency of steps Task achievement (all or some subtasks) Ask the audience what is wrong with this! 12/8/2018

Stopping Conditions P x C rule: P is probability of a user error on the subtask C is the cost of the error When P x C is small enough, we stop expanding Can also stop at “skill” steps, where the users actions are not reflective (conscious) Ask the audience what is wrong with this! 12/8/2018

Task Variations Optional tasks Waiting for Events Cycles Time-sharing Ask the audience what is wrong with this! 12/8/2018

Aside: situated action Not all activities fit the task decomposition hierarchy nicely Think about tidying a room (vs. cleaning) See an item, put it away Look at the arrangement of things, change it The arrangement of things suggests classifications... Your behavior is heavily influenced by the environment So don’t forget to observe real behavior when doing task analysis Ask the audience what is wrong with this! 12/8/2018

Knowledge-based analysis Basic idea: start with list of items, then organize into a taxonomy (often ends up being a hierarchy) e.g. driving: Steering wheel Seat belt Horn control Seats Windscreen Speedometer Dashboard Steering column Foot pedals... Ask the audience what is wrong with this! 12/8/2018

Knowledge-based analysis Controls: Steering wheel Horn control Speedometer Foot pedals… Structural Seats Seat belt Dashboard Steering column Windscreen Ask the audience what is wrong with this! 12/8/2018

Knowledge-based analysis Controls: Steering wheel Horn control Speedometer Foot pedals… Structural Seats Seat belt Dashboard Steering column Windscreen Ask the audience what is wrong with this! 12/8/2018

Producing a taxonomy Start with an exhaustive list Using existing taxonomies (e.g. parts catalog) Put the items on cards - have users arrange them Taxonomies can be captured with attribute - value pairs, some required, some optional TAKD (Task Analysis for Knowledge Description) produces a Task Descriptive Hierarchy (TDH).. Ask the audience what is wrong with this! 12/8/2018

TDH Conjunctives: wash/wipe AND function XOR wipe front wipers, rear wipers wash front washers, rear washers position XOR front front wipers, front washers rear rear wipers, rear washers Ask the audience what is wrong with this! 12/8/2018

More on TDH TDH can be applied to actions as well as objects. In comparison with HTA (Hierarchical Task Analysis), TDH Focuses on similarity of objects HTA groups objects which are related by the task HTA allows arbitrary repetition, TDH encourages uniqueness. Ask the audience what is wrong with this! 12/8/2018

KRG Once we have a TDH, we can describe tasks in quasi-english sentences, using the TDH terms as standard nouns and verbs. Idea is to describe the task at the right level of abstraction, with unambiguous terms. Sounds a lot like XML... Ask the audience what is wrong with this! 12/8/2018

Entity-relationship techniques Borrowed from OO databases Objects Concrete Objects Actors Composite Objects Actions Have at least a “patient” X (action is done to X) Often an “agent” (who does the action) May involve other objects “instruments” (agent) Sam planted the leeks (patient) with his spade (instrument) Ask the audience what is wrong with this! 12/8/2018

Objects Objects Concrete Objects Actors Composite Objects Composite objects are collections of objects “the team”, “the kit” - sets of things Composite objects may also be “tuples”, e.g. an office comprises desks, chairs, file cabinets... Ask the audience what is wrong with this! 12/8/2018

Actions-messages Messages are a very important kind of action because they often influence other actions People ask people to do things People commit to doing things We acknowledge completion of actions Speech-act theory studies this Ask the audience what is wrong with this! 12/8/2018

Entities and relationships Object Sam Actions: S1: drive tractor S2: dig carrots Relations: object-object location(pump3, glasshouse) Relations: action-event before(plant seed, germinate) triggers(water seed, germinates seed) Ask the audience what is wrong with this! 12/8/2018

Sources of information Existing documentation Observation in a worked example Interviews (create specific scenarios) Ask the audience what is wrong with this! 12/8/2018

Uses of task analysis Manuals and documentation Requirements capture for design Detailed UI design Ask the audience what is wrong with this! 12/8/2018

Summary Find your group members! Project proposals due Friday (JFC’s office mailbox) Task analysis is a way to understand work There are 3 different ways of approaching it (which can be used together to some extent) Ask the audience what is wrong with this! 12/8/2018