You must perform the following functions before you turn ...



Checklist for GraphsYou must perform the following functions before you turn in any reports. These actions are easy to do and can immensely improve the professional character of your report (Show Me). Please check off the following and turn this form in with your report. Reports will not be accepted for grading until you have undergone these checks and may be considered as “late” if they must be returned to you for lack of your attention to these details. FORMCHECKBOX Where possible and appropriate, multiple related curves are plotted on the same graph so that they can be readily compared. (How?) FORMCHECKBOX The graph background is white. (How?) FORMCHECKBOX The “Smoothed line” option is turned off. If no theoretical curve or appropriate curve fit, I have not connected the symbols or have connected them with straight lines (How?). FORMCHECKBOX Collected data are represented with symbols, and theoretical curves or digitized waveforms with lines (How?). FORMCHECKBOX Line modes, line thicknesses or symbols distinguish data sets, not colors (How?). FORMCHECKBOX The horizontal gridlines are removed from my plots (How?). FORMCHECKBOX Major tick marks are included on the axes to indicate the positions corresponding to the number labels (How?). FORMCHECKBOX The numbers on the x and y axes are large enough to read (How?). FORMCHECKBOX The scales on the x and y axes follow the 1, 2, 5 rule (How?). FORMCHECKBOX The x and y axes are labeled clearly with the information they represent and the correct units of the data (e.g. Frequency (Hz) or Pressure (dynes/cm2)) (How?). FORMCHECKBOX The y-axis labels (title and numbers) run vertically from the bottom of the plot to the top, rather than horizontally (How?). FORMCHECKBOX Greek letters, other special characters, or superscripts/subscripts are used, when necessary, in an axis title or elsewhere (How?). FORMCHECKBOX The legend for each curve describes only the distinguishing characteristic of the curve (e.g. “With Fibrinogen”, “Without Fibrinogen,” not “Cell Growth With Fibrinogen,” “Cell Growth Without Fibrinogen,” not “first data set,” “second data set,” and certainly not “series 1,” “series 2.”) (How?). FORMCHECKBOX No chart title is used unless multiple graphs appear in a single figure. (How?) FORMCHECKBOX The legend is on the plot area at a location where it does not cover any of the data. (How?) FORMCHECKBOX Where applicable, the legends appear in an order that follows the position of the curve on the plot (i.e., upper curve matches the topmost legend) (How?). FORMCHECKBOX Legends highlight only the aspect of the given curve that distinguish it from the other curves. (Generally, if all legends have a phrase in common, that phrasecan be removed). FORMCHECKBOX Unnecessary borders are removed, including: The border around the legend.The border around the plotting area.The border around the complete plot. (How?) FORMCHECKBOX Where applicable, bars representing standard deviation or standard error of my collected data are included (How?). FORMCHECKBOX Where reasonable, physical units for the axes allow the number labels to have a small number of digits (e.g. 10 GPa instead of 10E9 Pa or 10,000 MPa) (What?).Contents TOC \o "1-3" \h \z \u Motivation PAGEREF _Toc445051725 \h 2Multiple Curves PAGEREF _Toc445051726 \h 3Chart Title PAGEREF _Toc445051727 \h 5Changing the Plot Background PAGEREF _Toc445051728 \h 6Smoothed Line Option (Never use this option) PAGEREF _Toc445051729 \h 6Symbols and Theoretical Curves PAGEREF _Toc445051730 \h 7Line Modes and Thicknesses PAGEREF _Toc445051731 \h 8Grid Lines PAGEREF _Toc445051732 \h 8Tick Marks PAGEREF _Toc445051733 \h 8Fonts on the Axes PAGEREF _Toc445051734 \h 9One, Two, Five Rule PAGEREF _Toc445051735 \h 9Axis Titles PAGEREF _Toc445051736 \h 10Vertical Text PAGEREF _Toc445051737 \h 10Greek Letters, Superscripts and Subscripts PAGEREF _Toc445051738 \h 11Borders (Get rid of them) PAGEREF _Toc445051739 \h 11Data Legends PAGEREF _Toc445051740 \h 12Legend Position PAGEREF _Toc445051741 \h 13Series Order PAGEREF _Toc445051742 \h 14Standard Deviations PAGEREF _Toc445051743 \h 15Use of a Template PAGEREF _Toc445051744 \h 17MotivationGraphs are arguably the most powerful tool that you have available in technical writing and technical presentations. When properly used, they can convey a large amount of information to the reader quickly and effectively. Time invested into proper formatting of the graph is worthwhile not only because it makes the plots look better, but also because it makes the data more readily understandable and illustrates the point of your work more effectively. This document provides several basic guidelines for creating effective graphs and illustrates the steps required to make basic formatting changes in Excel.Figures 1 and 2 are two graphical representations of the same data set. Figure 1 uses the default format of Excel. In REF _Ref444765888 \h Figure 1, additional care has been taken to follow the guidelines. The plot in REF _Ref444765906 \h Figure 2 provides the reader with an immediate understanding of the underlying data.Figure SEQ Figure \* ARABIC 1: Graph generated with the Excel default format.Figure SEQ Figure \* ARABIC 2: Graph of the same data used in REF _Ref444765888 \h Figure 1, but following the guidelines. REF _Ref345842903 \h \* MERGEFORMAT Figure 3 shows a default-style Excel plot in which experimental data are compared to a theoretical curve. REF _Ref444765962 \h \* MERGEFORMAT Figure 4 presents the same information in a more professional style.Figure SEQ Figure \* ARABIC 3: Graph of theory and data generated in Excel default format.Figure SEQ Figure \* ARABIC 4: Graph of the same data used in REF _Ref345842903 \h Figure 3 but following the guidelines.Multiple CurvesIn general, multiple data sets that have the same x and y axes should be plotted on the same graph. A plot with multiple data sets (curves) allows the data sets to be easily compared to one another and requires much less manuscript space than multiple graphs. Each curve must have a distinguishing line mode and legend. Excel generally attempts to determine how your data are ordered when you make a plot. For example, if you have 4 columns of data and you highlight all four columns, then go to the Insert ribbon and click the small arrow next to the scatter plot icon in the Charts group ( REF _Ref345841802 \h Figure 6) and select the straight line-only style, Excel assumes that you wish to use the data in the first column for x-axis values and to use the other three columns as y-axis values for three separate curves. Sometimes you will need to manually tell Excel which data sets are to be used for x and y values on each curve.Figure SEQ Figure \* ARABIC 5: Selection of the straight line-only graph type (highlighted in green).To change the data you wish to plot, right click on the plot you have created and go to “Select data” to obtain the Select Data Source window shown in ( REF _Ref345841802 \h \* MERGEFORMAT Figure 6). Click on the series of interest to bring up the Edit Series window ( REF _Ref345841534 \h \* MERGEFORMAT Figure 7), and change the information as necessary. The example in REF _Ref345841534 \h \* MERGEFORMAT Figure 7 shows the information for a worksheet named “Young’s Equation,” where the x-axis values are in Column A from Row 32 to Row 46, and the y-axis values are in Column C from Row 32 to Row 46. The series name (which will be used as the legend for this curve) is “Long Stenosis.”Figure SEQ Figure \* ARABIC 6: The Select Data Source windowFigure SEQ Figure \* ARABIC 7: The Edit Series windowYou can click on the “Add” button in the Select Data Source window to create an additional curve. Select the x and y data values as described in the previous paragraph.Chart TitleChart titles are not necessary in a document when a figure caption refers only to a single graph. The chart title would be redundant to the figure caption. However, when a figure caption refers to multiple figures (e.g. Figure 12a and Figure 12b), the chart title can be used to distinguish the two subfigures. While the use of multiple curves on a single graph is generally preferred to multiple graphs, multiple graphs may be preferred or necessary under the following circumstances.The data sets are fundamentally different from one another because either the x-axes or the y-axes are different physical quantities.The ranges of one of the axes are too different from one another. For example, one data set of force as a function of time ranges from 1 N to 1000 N, while the other data set ranges from 0.1 N to 10 N. If you need the reader to see any detail in the second data set, it may need to be plotted on a different scale. However, you may consider the use of a log axis or the use of two axes (left and right).The number of curves that are presented on one graph is so large that the curves obscure one another and prevent the reader from visualizing the trends. Here, you must choose between eliminating some of the data sets or showing some of the data sets on a separate graph.You need a chart title under two circumstances:Your figure consists of multiple graphs, each of which illustrates the results of a different condition. For this type of figure, each graph should have a title that differentiates it from the other graphs. Do not generate multiple graphs if multiple curves are more appropriate.Your figure will be part of a PowerPoint presentation or other venue in which figure captions are not used.To remove a chart title, left click on it and hit the delete key. To create a chart title, left click on the graph and then left click on the + sign that appears to the upper right of the graph. This action brings up a menu of elements that you can add ( REF _Ref444947882 \h Figure 8).Figure SEQ Figure \* ARABIC 8: The Add Elements menuYou can also click on the graph, click on the Design tab, and use the “Add Chart Element” button in the “Chart Layouts” group at the upper left ( REF _Ref444947898 \h Figure 9).Figure SEQ Figure \* ARABIC 9: The Add Chart Elements button in the Chart Layouts group.Changing the Plot BackgroundThe background of your plot should be white or, in a PowerPoint presentation, the same color as the background of your master slide. If the background is a color other than white, left click on the colored area and hit the delete key to change it to white. To change it to any other color, left click on the area, elect “FORMAT” under the “CHART TOOLS” menu that appears, and click on the down-arrow next to “Shape Fill.” Then select the desired color ().Figure SEQ Figure \* ARABIC 10: The “CHART TOOLS” menu with the “Shape Fill” button.Smoothed Line Option (Never use this option)The “Smoothed Line” option connects data points with a “spline fit” of the data. This feature is almost never desirable in scientific writing. It usually has no scientific relevance to your data and it can mislead the reader. It can also lead to data points on the curve that are physically impossible (e.g. showing negative values for something that must be a positive quantity). To eliminate this option, right click on the data series in question, go to “Format Data Series…,” (or alternatively, double click on the data series) and use the menu that appears on the right side of the screen (Left side of REF _Ref444949649 \h Figure 11). Select the “Fill & Line” icon (the little paint can under “SERIES OPTIONS,” and expand the “LINE” menu. Go to the bottom of the menu and uncheck “Smoothed line.” Figure SEQ Figure \* ARABIC 11: The “Format Data Series…” menu with (Left) the ~LINE selected and (Right) the ~MARKER selected.Symbols and Theoretical CurvesCollected data should generally be presented as discrete symbols, and theoretical curves or curve fits should be presented as lines. Digitized data, such as the time series data that you might download from the oscilloscope, should also be presented as a line. To represent discrete data points with symbols, right click on the data series in question, go to “format data series.” You will obtain the “Format Data Series…” menu that was shown in REF _Ref444949649 \h Figure 11. Select the “Fill & Line” icon (the little paint can under “SERIES OPTIONS,” and expand the “LINE” menu. Select “No line.” Then click on “~Marker” button and click on “Built-In.” Under “Type,” select the shape of the marker that you wish to use. Now click on “Marker Fill,” select “Solid fill,” and use the down-arrow next to the “Color” box to select the desired color (usually black). In some cases, you may need to change the marker line color (the outline of the marker) to match the marker fill. To do so, go down to the “Border” section at the bottom of the menu and select the appropriate color under the “Color” drop down menu (not shown in the figure). You can distinguish different data sets by different symbols and different fill options. For example, squares vs. diamonds vs. triangles, or filled squares vs. open squares. Be consistent in selecting symbols. For example, if you are plotting x vs. y for two models at three different temperatures, you can make Model 1 always be filled symbols and Model 2 always be unfilled symbols and differentiate the temperatures as boxes, diamonds and triangles.Line Modes and ThicknessesWhenever possible, generate plots in black and white rather than color. While colors may look nice, they do not necessarily copy well. While you may believe that it does not matter because you plan to print your final thesis or report in color, consider that some people may have a black and white copy of your work and may miss important aspects of your work. If you are making a plot for a presentation, remember that some colors do not appear at all when displayed on computer projectors, leading you to tell your audience, with great embarrassment, that “It looks fine on my computer screen.” You will then have to explain to them what the data set “would look like” if they could see it. To change the character of plotted curves, bring up the menu on the left side of REF _Ref444949649 \h \* MERGEFORMAT Figure 11. Select the various options as appropriate.Note: If you are plotting a large number of points, the dashed and dotted line mode options will not work correctly. You can make it work correctly if you reduce the number of points in your data set (e.g., keeping only every 5th point). One simple way to do reduce the number of points is to highlight the data points that you want to keep (using CTRL+left-click), then use copy, and then past the results to another location in the spreadsheet.Grid LinesBy default, Excel plots have horizontal gridlines in them. These lines are distracting and should be removed. To do so, click on one of the lines and hit the Delete key. Alternatively, you can right click on the grid lines and scroll down to “Delete.”Tick MarksAlthough the horizontal gridlines are distracting, it is necessary to include the “major tick marks” on the axes. The tick marks indicate the locations that correspond to the number labels. You should not, however, include “minor tick marks.” If the major tick marks do not appear, double click on the axis (or right click on it, select “Format Axis…,”) and select “Axis Options” ( REF _Ref444954454 \h Figure 12) in the left hand window (the icon that looks like a bar graph), and select “Outside” under “Major tick mark type.” You should also select “None” under “Minor tick mark type.”Another annoying feature of Excel is that the axis may be gray instead of black. To change the axis lines to black, double click on the axis and select the “Fill & line” icon (paint can), then select black instead of gray in the drop-down menu labeled “Color.” Figure SEQ Figure \* ARABIC 12: The “Format Axis” menu. (Left) Axis options. (Right) Fill & line.Fonts on the AxesFonts on the axes, for both the numbers and axis titles, need to be large enough for the reader to see clearly. For a document, a font size of 11 or 12 is usually sufficient. For a PowerPoint presentation, the fonts may need to be larger so that they can be easily read by people in the back of the room. To change the font size on an axis title, right click on the label and go to “Font.” The options on this menu are generally straightforward.One, Two, Five RuleThe axes of graphs are most easily read if they are labeled in increments of 1, 2 or 5. (This scheme works well because we live in a base 10 society where we are familiar with breaking things up into 10 subunits and because 2 and 5 are the factors of 10). For example, if the data range from -13 to 17, a good label scheme would make the axis range from -15 to +20 with labels at -15, -10, -5, 0, 5, 10, 15, and 20 (increments by 5s). You generally do not want to have more than 7 labels on your plot, so an acceptable alternative would be to set a scale from -20 to +20 and have labels at -20, -10, 0, 10 and 20 (increments by 1 s). Axes that are labeled in other increments (e.g. 3, 4, or 2.4032) are difficult to interpolate by eye. Furthermore, your scale should include a number label at 0.The axis scale is controlled by the “Axis options” menu shown on the left side of REF _Ref444954454 \h Figure 12. Fill in appropriate values for “Minimum,” “Maximum,” and “Major unit.” E.g., for the first scaling in the paragraph above, Minimum would be -15, Maximum would be 20, and Major unit would be 5.Use units that yield number labels in the range of 0.01 to 1000, if possible. For example, if you are comparing cell diameters, use ?m rather than meters.Avoid exponential notation if possible. If your y-axis ranges from 0 to 10,000,000 Pa, for example, you can change the units to MPa so that the y-axis will range from 0 to 10 MPa. Similarly, the reader will more easily understand a plot for which the time axis ranges from 0 to 0.00000001 seconds of the axis units are changed to nsec, so that the range is from 0 to 10 nsec.Do not add trailing zeros to the numbers on your axis labels. If your axis has labels at 0, 2, 4, and 8, do not label them as 0.0, 2.0, 4.0 and 8.0. Axis TitlesThe x- and y-axes should be labeled with the name and units of the axis quantity. To label the axes (e.g. “Pressure (mm Hg)”), use the “Axis titles” option shown in REF _Ref444947882 \h Figure 8. Edit the title fields as needed. Never assume that the physical quantity and dimensions of an axis are obvious. Even something as obvious as “Volts” might be plotted in milli-Volts or kilo-Volts. Vertical TextExcel allows you to change the orientation of text. To do so, right click on the text, go to “Format axis” or “Format axis title” and hit the “Alignment” tab. Type in the needed angle of rotation in the box labeled “Custom Angle.” Excel orients axis titles and labels rationally by default, but in rare occasions, you may need to change this orientation. Double click on the item that you want to rotate and select the “Size and properties” icon, which looks like a square with dimension bars above and to the left of it ( REF _Ref444956296 \h Figure 13). Now modify the “Custom angle” as needed.Figure SEQ Figure \* ARABIC 13: Format axis size and properties menu.Greek Letters, Superscripts and SubscriptsExcel allows you to use Greek letters in the x and y axis titles. To take advantage of this feature, you should first type the axis title in its approximate form. For example, enter “dynes/cm2” as “dynes/cm2.” Now highlight the character or characters that you need to modify (e.g., the “2” in this example) and use the Font group on the HOME ribbon (left side of REF _Ref445033407 \h \* MERGEFORMAT Figure 14) to make the needed modifications. When you click on the lower right hand corner of this group, the advanced font menu appears (right side of REF _Ref445033407 \h \* MERGEFORMAT Figure 14). To change a character into Greek, type “symbol” into the box labeld “Calibri (Body)” in REF _Ref445033407 \h \* MERGEFORMAT Figure 14. When this font is selected, western characters are changed to Greek. For example, “a” is changed to “?,” and “D” is changed to “?.” Thus, you can enter “?P (dynes/cm2)” by first entering “DP (dynes/cm2)” and then changing the “D” to its Greek equivalent and changing the “2” to be a superscript. Figure SEQ Figure \* ARABIC 14: (Left) the Font group of the HOME ribbon. (Right) the advanced Font menu.Borders (Get rid of them)Extra borders are unnecessary and generally distracting. They can also interfere with important information. Compare, for example, the two plot styles shown in Figures 5 and 6. The data and other information are better emphasized when the following are eliminated:The border around the legend (labeled “1” in REF _Ref445033877 \h Figure 15).The border around the plotting area (labeled “2” in REF _Ref445033877 \h Figure 15).The border around the complete plot (labeled “3” in REF _Ref445033877 \h Figure 15).Figure SEQ Figure \* ARABIC 15: Plot with unnecessary borders.Figure SEQ Figure \* ARABIC 16: Plot without unnecessary borders.To remove the border around each of these elements, double click on the border to bring up Chart Tools and select the Format tab ( REF _Ref445034113 \h Figure 10). Click on the down-arrow next to “Shape Outline” and scroll down to “No Outline.” Whenever you remove the border around the plotting area, you need to click on either the top or the right line so that you do not remove one of the axis lines instead of the plot frame. Data LegendsChoose data legends carefully so that they identify the aspect of the associated curve that is unique to that data set. Do not duplicate information from the figure caption, the axis labels, or the chart title (if you needed one) in the legend. For example, if you are comparing cell growth with fibrinogen (one curve) to cell growth without fibrinogen (the other curve), you need only label the curves as “With Fibrinogen” and “Without Fibrinogen.” The words “cell growth” is not needed because both curves present cell growth, and that information will appear either in the figure caption or the y-axis label. To change the legends associated with each data set, right click on the plot and go to “Select Data,” which brings up the Select Data Source menu ( REF _Ref445036901 \h Figure 17). Click on the data set you wish to change in the window labeled “Legend Entries (Series).” (The data sets are usually labeled “series1, series2, series3, etc. by default, unless you have put legends in the first row of the data series). Then, click on “Edit” and type the legend into the top box of the next dialogue box and click on “OK.” Figure SEQ Figure \* ARABIC 17: The Select Data Source menu.Legend PositionThe best location for a plot legend is usually on the plotting area itself, but in a location that is away from any of the plotted data. To change the position of a legend, simply left click on the legend and drag it to the position you desire. You should not place the legend off of the plot area because it takes up extra room unnecessarily and leaves less room for the plot itself. Consider, for example, the two plots shown in REF _Ref445036171 \h Figure 18, where the upper plot is more readable. The only danger with this method is that you may place the legend too close to the curves, which leads to a cluttered appearance. In some cases the plot may not have a large enough empty region to accommodate the legend. Even in those cases, you can often simply extend the x or y axis to create room for the legendFigure SEQ Figure \* ARABIC 18: Positioning of the legend on the plot area (top) instead of to the side (bottom) allows the plot to be larger.Series OrderIt is natural for a reader to assume that when several curves appear, the uppermost curve will correspond to the uppermost legend. Examples of incorrect and correct legend positions are shown in Figures 18 and 19. In REF _Ref445036527 \h Figure 18, the top curve corresponds to the 5 kg mass, which is the bottom legend. In REF _Ref445036582 \h Figure 19, the top curve corresponds, more logically, to the top legend.To change the position of the legend, right click on the plot and go to “Select Data.” In the Select Data Source menu ( REF _Ref445036901 \h Figure 17), click on a data set that you wish to reposition, and use the up and down arrows (next to the “Remove” button) to move the legend position.Figure SEQ Figure \* ARABIC 18: Graph with inappropriate legend order (upper legend corresponds to Lower curve).Figure SEQ Figure \* ARABIC 19: Graph with appropriate legend order (upper legend corresponds to upper curve).Figure SEQ Figure \* ARABIC 18: Graph with inappropriate legend order (upper legend corresponds to Lower curve).Figure SEQ Figure \* ARABIC 19: Graph with appropriate legend order (upper legend corresponds to upper curve).Standard DeviationsWhenever repeated measurements are made at a given set of parameters, it will be important for the reader to know not only the mean value of each data point, but also the standard deviation or standard error, whichever is appropriate. An example plot with standard deviations included is shown in REF _Ref445039877 \h Figure 21. Figure SEQ Figure \* ARABIC 21: Graph that uses error bars to represent the standard deviations of collected data sets.Figure SEQ Figure \* ARABIC 21: Graph that uses error bars to represent the standard deviations of collected data sets.To add error bars to a data set, left click on the data set and then left click on the + sign to the upper right of the graph to bring up the Chart Elements menu ( REF _Ref444947882 \h Figure 8). Scroll down to “Error Bars” and left click on the rightward pointing arrow that appears. Scroll down to “More Options,” and left click again. This process brings up the “Format Error Bars” menu ( REF _Ref445039132 \h Figure 22). The options “Both” and “Cap” shown in REF _Ref445039132 \h Figure 22 are probably desirable. Typically, you will have a different standard deviation for each data point, so you should select “Custom” under “Error Amount” and then left click on “Specify Value.” Under “Positive Error Value” and “Negative Error Value,” you can specify a range of cells on your Excel sheet that corresponds to the data value positions in the given series. Click OK after these ranges have been selected. Typically, you will specify the same range of cells for both entries (i.e., the positive error is the same as the negative error). If you have horizontal error bars in addition to the vertical error bars, left click on the horizontal error bars and hit delete to remove them. Be careful not to remove the entire data set, however.Figure SEQ Figure \* ARABIC 22: The Format Error Bars menu.Figure SEQ Figure \* ARABIC 23: Menu to specify the values for custom error bars.Use of a TemplateThe addition of axis titles and major tick marks, along with removal of extraneous boxes, can be tedious. One workaround is the use of a template. One example is shown in REF _Ref445050810 \h Figure 24. Copy this graph and paste it into Excel. Then right-click on the plot area and scroll down to “Save as Template…” Save the template to an appropriate file name. I have used the name “SimpleChart.” Now, when you want to create a new graph, generate the graph and double-click on it. Click on the “Change Chart Type” button on the “Chart Tools” “Design” tab. Click on “Templates,” and select the plot corresponding to your template (SimplePlot in my case). This process will not yield a perfect plot, but it will take care of some of the more annoying changes that you tend to make nearly every time you create a graph.Figure SEQ Figure \* ARABIC 24: Example template for ExcelFigure SEQ Figure \* ARABIC 25: The Change Chart Type button on the Chart Tools Design tab.Figure SEQ Figure \* ARABIC 26: The “Change Chart Type” menu with “Templates” selected. ................
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