1、Selecting right graphics for your purposesDesigning graphics:tables,graphs,charts&grahpic illusrationAvoiding visual distortion:presenting real picture,presenting the complete picture,avoiding distorted emphasis.I.TablesTables systematically present information in and.This information can consist of
2、 either words or numbers.Tables composed of words are called,while those composed of numbers are.1.Prose TablesProse tables present qualitative information(prose descriptions,explanations,or instructions).e.g.Figure 8-1 Prose Table Troubleshooting Guide Before Requesting ServiceCheck the following p
3、oints once again if you are having some trouble with your TV.ProblemSolutionNo power.Check that the Power plug is completely connected to an AC outlet.Check that the Power button on TV is set to ON.No sound Headphones may be plugged in.Remove headphones.Snowy pictures Check if the direction of the a
4、erial has changed.Reset the aerial.The aerial lead-in may be broken or disconnected.Reconnect the aerial lead-in.Remote control does not work.Batteries in the remote control may be exhausted.Replace batteries.Batteries may be improperly installed.Reinstall batteries correctly.2.Numerical tablesNumer
5、ical tables present quantitative informationdata that can be measured.Items are grouped so that comparisons and relationships can be determined.E.g.Comparison of Subtests between the Treatment Group and the Control GroupResults bListeningVocabularyClozeReadingWritingMeans of Control Group12.06458.53
6、236.790326.90328.2258Means of Treatment Group11.48394.90324.370422.33878.9355Std.Deviation of Control Group3.28312.04911.20265.46111.5856Std.Deviation of Treatment Group2.54132.05921.86364.43921.3889Subtest aa All subtests were conducted for both groups at the same time.b The results were obtained v
7、ia the double-blind method.3.Guidelines for TablesSince tables often present a sizable body of specific facts,they must be carefully constructed so that they are as clear as possible.The following guidelines can help you make your tables effective:Provide a title describing exactly what is being com
8、pared or measured,and label stub heads,column heads,and row heads clearly so readers know what they are looking at.Use familiar symbols and abbreviations($,hr.,No.).Define specialized symbols or abbreviations(A for angstrom,db for decibel)in a footnote.Change fractions into decimals and align decima
9、ls and all numerical values vertically.Keep decimal places for all numbers equal.Round insignificant decimals to the nearest whole number.Columns are easier to compare than rows.Therefore,compare data vertically(in columns)instead of horizontally(in rows).Keep prose entries as brief as clarity allow
10、s.List the items in a logical order(alphabetical,chronological,increasing or decreasing),and space listed items for easy comparison.Use X,NA(not available,not applicable),or a dash to signify any omitted entry,and use footnotes to explain entries,abbreviations,or omissions.Label footnotes with lower
11、case letters so readers do not confuse the notation with the numerical data.Limit the table to one page.Otherwise,write“continues”at the bottom,and begin the second page with the full title,“continued”,and the original column headings.Graphs Graphs translate numbers into shapes,shades,and patterns,a
12、nd display them in a coordinate system.A graph displays the approximate values,the point being made about those values,and the relationship being emphasized.Graphs are especially useful for depicting comparisons,changes over time,patterns,or trends.In a graph,the horizontal axis shows categories(the
13、 independent variables)to be compared,such as years within a period;the vertical axis shows the range of values(the dependent variables)for comparing or measuring the categories,such as the rice production in a given year.A dependent variable changes according to activity in the independent variable
14、,such as an increase in production over a set period.1.Bar GraphsA bar graph is used to display comparisons between a relatively small number of discrete data items.Properly labeled bar graphs allow the reader to see the trends and the precise value of specific points in a graph.There are five impor
15、tant varieties of bar graphs:the simple bar graph,the multiple bar graph,the stacked bar graph,the horizontal bar graph,and the deviation bar graph.Simple Bar GraphA simple bar graph displays one trend or theme.Some range of comparison is put on the y-axis(such as time,cost,or temperature),and items
16、 being compared are put on the x-axis.Multiple Bar Graph012345678910East SouthWest NorthSales(in millions)RegionsSales by Quarter1st2nd3rd4thStacked Bar Graph05101520253035East SouthWest NorthSales(in millions)RegionsSales by Quarters4th3rd2nd1stHorizontal Bar GraphExpected Computer Life0123456a1b4c
17、6d9e12f13g21Computer TypesUsable YearsDeviation Bar Graph A deviation bar graph displays both positive and negative values.E.g.Percent Changes in Employment(1980-2000)-40-2002040AgricultureMiningManufacturingInsuranceTransportationFinanceRetail tradeConstructionServicesPercent Change Profession Manu
18、facturingGuidelines for Bar Graphs Use bar graphs only to compare values that are noticeably different.Bars with small value differences will look too similar to compare.Make all bars the same width to avoid confusion.If you require emphasis,be aware that darker bars are seen as larger,denser,and mo
19、re important than lighter bars of the same size.Number your scales in units familiar to the audience.Space the numbers equally.Label both scales to show what is being measured or compared.If space allows,keep all labels horizontal for easier reading.Use tick marks to show the points of division on y
20、our scale.If the graph has many bars,extend the tick marks into grid lines to help readers relate bars to values.Keep the graph simple and easy to read.Do not put more than four types of bars in each cluster in a multiple bar graph.In a multiple bar graph,use a different pattern,color,or shade for e
21、ach bar in a cluster.Provide a key,or legend,identifying each pattern,color,or shade.Avoid needless visual details.Showing off every possible type style,all the shading patterns,and three-dimensional enhancements in bar graphs can only lead to confusing presentations that fail to communicate clearly
22、 with the reader.A Graph with Chartjunk02004006008001000JanFebMarAprMayJunMonthly ProductionGraph Without ChartjunkMonthly Production02004006008001000JanFebMarAprMayJun 2.Line GraphsA line graph provides many more data points than a bar graph.It helps readers synthesize large bodies of information i
23、n which exact quantities do not need to be emphasized.It implies the continuity of data and indicates any changes in it,thus providing quick information about trends.There are three important varieties of line graphs:single line graphs,multiple line graphs,and deviation line graphs.Single Line Graph
24、Hourly Temperature051015202530354091011121314151617HoursTemperature CIn a single line graph,information about one thing is represented.Very often the x-axis represents different points in time(independent variables)and the graph as a whole shows the development over time of an event.Multiple Line Gr
25、aphA multiple line graph displays several relationships simultaneously.A significant advantage of this graph is its ability to plot multiple trends.A caption is usually included to explain the relationships readers are supposed to see.020406080100195019601970198019902000PercentLabor Force Participat
26、ion Rate by Sex(1950-2000)MenTotalWomenThe labor force participation rate for men declines as the rate for women increases.Deviation Line Graph A deviation line graph extends the vertical scale below the zero baseline to display both positive and negative values in one graph.Percent Changes in Produ
27、ct Increase-6-4-202468101999200020012002200320042005YearPercentGuidelines for Line Graph Guidelines for Line Graphs.Follow these guidelines for line graphs:Make each line visually distinct from others.Label each line so that users know what it represents.Display no more than three or four lines on o
28、ne graph.Mark each individual data point used in plotting each line.Avoid using grid lines that users could mistake for plotted lines.3.Scatter GraphsScatter graphs use single,unconnected dots or points to express the relationship between two variables.If the variables are correlated,the points in t
29、he graph will fall along a line or curve.The better the correlation,the tighter the points will hug the line.If the points are primarily on a diagonal running from the lower left to the upper right,the correlation is positive.If the points run from the upper left toward the lower right,the correlati
30、on is negative.If the points are randomly scattered,there is little or no correlation between the two variables.Example 1The Students Study Time and Their ScoresStudent No123456789101112Study Time(hours)154318122533271732474045Exam Scores388366576864554278816893Relationship between the Students Stud
31、y Time and Their Exam Scores02040608010001020304050Exam ScoresStudy TimeStudy Time vs.Exam ScoresExample 2 Relationship between Product Prices and Sales Volumes0200400600050100150200250SalesPrices Prices vs.SalesGuidelines for Scatter Graph Scatter graphs demonstrate whether there is a trend of nume
32、rical correlation between two sets of variables.Use scatter graphs when you need to compare large amount of data without considering time.The more data in the graph,the better the comparison of results.Since the scatter graph presents coordinate points,two or more sequences of data presented in one
33、graph may cause confusion.Therefore,for two or more sequences of comparison,youd better use the line graph.ChartsThe terms chart and graph are often used interchangeably.However,a chart displays relationships(quantitative or cause-and-effect)that are not plotted on the coordinate system(x-and y-axes
34、)used in graphs.1.Pie Charts A pie chart displays the relationship of parts or percentages to the whole.Readers can compare the parts to each other as well as to the whole.E.g.41%30%9%7%13%College Expenses for StudentsTuitionRoom&boardFeesBooks&suppliesOtherGuidelines for Pie Charts Make certain tha
35、t the parts add up to 100 percent.Use different colors or shades to differentiate each slice clearly.Include a key or legend to help readers identify each slice,or label each slice directly.Keep all labels horizontal for easier reading.Include no less than two and no more than eight segments.A pie c
36、hart with more than eight segments can be hard to interpret.If you have more than eight segments,combine very small segments under the heading“Other”.2.Flow Charts A flow chart traces a procedure or process from beginning to end.E.g.Flow Chart for the Process of Computer-Based LearningStartLearn Cou
37、rseTake Unit TestNPassYEnter Next UnitReady for TutoringYReceive TutoringGo on LearningYPass TutoringN3.Organization Chart An organization chart shows the hierarchy and relationships between different departments and other units in an organization.Grade GroupsTeaching and Research GroupGrade GroupsP
38、rinting RoomFinancial OfficeHeadmasters OfficeStudent Affairs OfficeTeaching Affairs OfficeGeneral Affairs OfficeBoard OfficeClass DeansClass Deans 4.Tree Charts A tree chart shows how the parts of an idea or concept connect to each other,so that users can better visualize their relationships.Tree C
39、hart for Classification of GraphsLine graphsDeviation line graphsMultiple line graphsSimple line graphsGraphsDeviation bar graphsHorizontal bar graphsMultiple bar graphsBar graphsSimple bar graphs.Graphic IllustrationsThe most familiar visual presentations are photographs and diagrams that depict th
40、e actual appearance of subjects.Photographs and diagrams show subjects exactly as we expect them to appear in life.Each of these forms has a significant role in technical illustration.1.PhotographsPhotographs contain every detail that readers might be able to observe as if they were observing the su
41、bject in person.They are the most realistic of all illustrations.However,photographs can be so information-rich that they can be confusing,making it hard to identify what you really want the reader to see and what is the most important featureExamplePhotograph of a Recorder Motor with Too Many Detai
42、ls Guidelines to use photographs effectively Take the photograph at the right angle of vision so that readers can identify or view the item they are supposed to see.Label all the parts readers need to identify.Trim the photograph to eliminate needless details.Figure 1 Too many details.Figure 2 Unnec
43、essary Details Trimmed Provide a frame of reference by including a person,a hand,a tool,or other familiar objects in the photo.A person with her hands showing how something is done.Number the photograph in its order of appearance,and include a prose caption if necessary.(E.g.Figure 1,Figure 2)2.Diag
44、ramsA diagram is a sketch or drawing designed to demonstrate how something works or to clarify the relationship between the parts of a whole.Diagrams offer almost the same level of realism as photographs;they also allow you to stress aspects of your subject by eliminating irrelevant and distracting
45、details.Because they are easily understood,simply created and easily integrated within text,diagrams are the most popular choice for technical illustration.There are two types of diagrams:cutaway diagrams and exploded diagrams.Cutaway DiagramCutaway diagrams depict subjects with the exterior layers
46、removed in order to reveal interior sections.Such diagrams can be particularly effective because the cut-away portion provides a context for the part that is shown.In this way,the reader not only sees the details underneath,but also understands how the details fit into the larger context of the subj
47、ect.Example:Cutaway Diagram of the Nose and the BrainPituitary gland and tumor脑下垂体和肿瘤Sphenoid sinus蝶窦Nasal septum鼻中隔Exploded DiagramAn exploded diagram shows how the parts of an object are assembled.Such diagrams show what the inside of the object is like and how each part is connected to other part
48、s.Since exploded diagrams provide a clear context for subassemblies,they are often used in repair or maintenance manuals.Example:Exploded Diagram of a RocketForward segmentForward mid segmentAFT mid segmentAFT segment with nozzleNose capFrustumForward skirtAFT skirt.Avoiding Visual DistortionAfter s
49、electing the appropriate means in presenting data,you should make sure that the data is presented accurately and objectively.The same set of data can support contradictory conclusions if presented in different ways.Even though your numbers may be accurate,your visual display could be misleading.Pres
50、enting your data in a distorted graph is unethical,so you should try your best to avoid misrepresentation.1.Presenting the Real PictureVisual relationships in a graph should accurately express the numerical relationships they represent.Normally,you should begin the vertical scale at zero and never c
