Hierarchical Task Analysis: Breaking Down Complex Tasks into Subtasks, Slides of Process Engineering

Download Hierarchical Task Analysis: Breaking Down Complex Tasks into Subtasks and more Slides Process Engineering in PDF only on Docsity! Hierarchical Task analysis Docsity.com Introduction • What are Tasks – What the user has to do (or thinks what he/she has to do) in order to accomplish a goal – Each task should be • Meaningful • Associated with a goal • Identifiable by the user • What is Task Analysis – A process of analyzing the way people perform their tasks • The things they do • The things they act on • The things they need to know 2 Docsity.com 0. Clean the house 1. Get the vacuum cleaner out 2. Get the appropriate attachment 3. Clean the rooms 3.1. Clean the hall 3.2. Clean the living rooms 3.3. Clean the bedrooms 4. Empty the dust bag 5. Put vacuum cleaner and attachments away Plans Plan 0: do 1 - 2 - 3 - 5 in that order. When the dust bag gets full do 4 Plan 3: do any of 3.1, 3.2 or 3.3 in any order depending on which rooms need cleaning 5 Textual HTA of the Task of Cleaning a House • Indentation is used to denote the levels in the task hierarchy • Plans are labeled by the tasks they correspond to • Only the plans denote the order of task performance • Not all subtasks need to performed, and not necessarily in the order presented in the hierarchy Docsity.com 6 0. Clean the house 1. Get the vacuum cleaner out 2. Fix the appropriate attachment 3. Clean the rooms 4. Empty the dust bag 5. Put vacuum cleaner and attachments away Plan 0: do 1 - 2 - 3 - 5 in that order. when the dust bag gets full do 4 3.1. Clean the hall 3.2 Clean the living room 3.3. Clean the bedrooms Plan 3: do any of 3.1, 3.2 or 3.3 in any order depending on which rooms need cleaning Diagrammatic HTA of the Task of Cleaning a House Docsity.com Generating Hierarchy • Identify the Major Task to be Analyzed – e.g. clean house, purchase a flight ticket online, copy a ten-page paper, etc. • Break Down the Major Task into Subtasks – What subtasks must be accomplished in order to perform the main task – Refer to various sources (e.g. direct observation, expert opinion, documentation, etc.) – Try to be specific in terms of the objectives of subtasks • Decide Upon the Level of Detail into Which to Further Decompose the Subtasks – Some stopping rule i h i i 7 Docsity.com 10 0. Make a cup of tea 1. Boil water 2. Empty pot 3. Put tea leaves in pot 4. Pour in boiling water 5. Wait for 4 or 5 minutes Plan 0: do 1 At the same time, if the pot is full, do 2 Then do 3 – 4 After four or five minutes do 6 HTA of the Task of Making a Cup of Tea 6. Pour tea Plan 1: do 1.1 – 1.2 – 1.3 when kettle boils, do 1.4 1.1. Fill kettle 1.2 Put kettle on stove 1.3. Wait for kettle to boil 1.4. Turn off gas Any omission or error? Can some first-level subtasks be combined ? Docsity.com 11 1. Boil water 2. Empty pot 3. Make pot of tea 3.2. Pour in boiling water 4. Wait for 4 or 5 minutes 1.1. Fill kettle 1.2 Put kettle on stove 1.4. Wait for kettle to boil 5. Pour tea Plan 1: do 1.1 – 1.2 – 1.3 – 1.4 when kettle boils, do 1.5 1.5. Turn off gas 3.1. Warm pot 3.2. Put tea leaves in pot Plan 3: do 3.1 – 3.2 – 3.3 1.3. Turn on gas Can we expand 5? 0. make a cup of tea Plan 0: do 1 At the same time, if the pot is full, do 2 Then do 3 – 4 After four or five minutes do 5 Docsity.com 12 Suppose subtask 5 “Pour tea” can be further decomposed 5. Pour tea 5.1. put milk in cup 5.2. fill cup with tea 5.3. add sugar to taste Plan 5. Do 5.1 – 5.2 – 5.3 What if we want to make more than one cup? 5.1 5.2 More cup(s)? Yes 5.3 Docsity.com Types of Plan • Fixed Sequence – The same sequence of subtasks is always followed • e.g. Plan 3 in the HTA of tea making • Optional Subtasks – Subtasks that may or may not be performed depending on circumstances • e.g. Subtask 2 in plan 0 in the HTA of tea making • Waiting-For Events – Wait for a certain time • e.g. Wait for 4 or 5 minutes in plan 0 in the HTA of tea making Wit f th f t 15 Docsity.com Types of Plan • Cycles – Repeat some subtasks until a condition is reached • e.g. Repeatedly perform subtasks 5.1 – 5.3 until no more cup is left in the HTA of tea making • Time Sharing – Some subtasks can be done at the same time • e.g. Subtasks 1 and 2 can be done at the same time in the HTA of tea making • Discretionary Subtasks – Whether to perform some subtasks is at the people’s discretion • e.g. In plan 3 in the HTA of room cleaning, the person is 16 Docsity.com