Don't worry - Mistakes are ok

The message here is to try everything.  Click all over the place.  Pull down all sorts of menus and experiment to your hearts content.  You are not going to break Excel or break your computer with this experimenting.  The worst thing that can happen is that you make a nonsense document that you put into the trash.  Then you can download another copy of the original.  

If you don't want to download the same workbook repeatedly, make a copy of the particular sheet you are working on.  Go to the Edit menu and choose Move or Copy Sheet.  Make sure you have filled in the checkbox next to Create a copy.  

Also note that Excel allows you to "Undo" and that in fact you can go backwards quite a few steps.  So if you make a mistake, you can often just do it over.  The Undo item is also in the Edit menu. 

Unprotecting and Protecting Sheets

In  this case protection does not refer to copyright. If you want to control materials for which you hold the copyright, don't put them online in this manner.  

The Excel document (or worksheet) can be considered from the vantage of the student user or the alternative vantage of the faculty author/editor.  (Obviously, students can author and faculty can use the student creations, but for illustration purposes it's helpful to envision it as stated here.)  The users don't really want to go into edit mode --- that is an inconvenience they'd like to avoid.  They want to do their work and get out.  So the author/editor protects the document in order that the student doesn't have to hassle with the document.  

Since now you are reverse engineering the worksheet, you want to unprotect it.  Go to the Tools menu and choose first Protection and then Unprotect Sheet.  

If you end up making something that you would like others to use, you'll want to go back and protect the sheet.  I have chosen to protect Objects only - the charts and the buttons.  You can protect other things as well.  That is your choice.  I figure that if the students want to change the numbers or formulas in the cells, more power to them.

Spinner and Spin Button

The up and down button with arrows on it is referred to as the spinner.  It looks like this  

The spinner is found on the Forms toolbar.  All toolbars are found on the View menu.  The Forms toolbar is on both Mac and PC and the core explanation of the function will be given for the spinner.  The spinner has a cousin called the spin button.  It is found on the Control Toolbox (PC Only) and looks like this.     

These are tools I was unfamiliar with until I started making the Excelets.  They have remarkably similar functionality.  Their primary mission is to advance or reduce values in a cell faster than can be done via typing.  Both tools perform that function equally well.  Where they differ is on how the graphs interpret that altered numeric data.

While these buttons can be controlled in other ways, there are three basic things you need to control with these buttons.
1. The linked cell.  Where are you entering the data?
2. The minimum value of the data range.  The default is 0 and I almost always use that.  Occasionally, I'll change that to 1.
3.  The maximum value of the data range.  I have been using 100 for the maximum. I use the default for the data to advance by 1 unit, so there are 100 (really 101) values in most of my series.  Occasionally there are less.  It is rare for there to be more.  These movies are short.  They are conveying some disciplinary point and that is it.  This is not cinema that people would go to see for entertainment.  (I tested some of these on my kids and my wife and they found them extremely boring, in spite of my obvious pride as the creator.)  So the movies need to be brief.  100 values is plenty.

To make new spinners select the button from the Forms toolbar and then drag on your spreadsheet to insert the button and determine its shape.  You can move the button around afterward to position it on the spreadsheet.

To enter these parameters right click on the spinner button (on a Mac with a single button, use Ctrl and click).  You should see white dots around it and a menu.  Choose Format Control and then make sure the Control tab has been selected.  You should see something like what we have below, which is for a button that has yet to be formatted, with the defaults filled in.

Leave the Minimum value box alone.  Type 100 into the Maximum value box.  The Incremental change box should be left at 1.  Click the color button to the right of the Cell link line.  This will take you out of the screen and back to the spreadsheet itself.  Find the cell where you want the values created and click on that.  There should be a dashed line around that cell.  You should also see a Format Control bar and it should have the address of the cell you just selected.  Click the color button on that bar.  Then click the OK button at the bottom of the Format Control window.  You should be back at your spreadsheet.  Click anywhere on the spreadsheet other than on your button.  It should now be activated.  Test it out.

The procedure is essentially the same for the spin button.  With the control toolbox in view select the triangle/pencil button which puts you into Design Mode.  When you are done you will select this button again so you get out of Design Mode and can use the controls you created.  You make spin buttons by selecting that button from the Control Toolbox and dragging it onto the screen, when in Design Mode.  You can position and size the spin button and afterward reposition it on the worksheet. 

In Design Mode, right click on the spin button.  Select Properties from the menu.  You should see something like below.

This is complex looking, but it really isn't too bad.  The defaults should work for you.  Find the LinkedCell line and type in the address of that Cell in the blank space.  So you have to know which cell you want the values to appear in  beforehand.  Now you can close out this box.  And exit design mode. Then test out the button.

Tip:  You will note that in my Excelets the Incremental Change is always 1 and formulas for values that are plotted are determined in other cells that refer to the cell that is controlled by the spinner.  I don't use the spinner to control those values directly.  The reason for this is that in creating the animation, it is hard to know in advance if the graph movie will play too fast or too slow for good viewing.  It is easier to change the formula in the linked Cell, than to adjust the values in the spinner.  For example, suppose the spinner controls the cell D18.  And suppose that in the linked cell I have a formula such as: =3+.01*D18.  This formula would in effect vary the values from 3 to 4 with increments of .01.  If this proves too slow, I can change the .01 to .02 or .05 and perhaps change the 3 to a 2.  Similarly, I can change the formula if the movie plays too fast.  

How does it work?  Selecting the Graph

Most of the Excel graphs I know about that are used for Higher Education are in Bar graph format and are used to display a categorical variable on one axis (as in responses to a Likert-scale survey question) and a numeric value (as in number who chose that response) on the other axis.  Grade data for an exam are also displayed in Bar graph format, for a histogram of the results.  Excelets can be made for Bar graphs, and I have one of these in my Elasticity module (in construction).  But most of what is featured in my microeconomics Excelets is in XY (Scatter)  format --- primarily with curve fitting of the points or with adjacent points connected by a straight line segment.  This may be a less familiar use of the Excel graph tool to most.  It brings recollections of high school analytic geometry.  I have found that it allows a substantial amount of control of how the graph will ultimately look and how the animation plays, but because of the unfamiliarity, it will take some getting used to.     

To make matters concrete, let's use the ConsumerOptimumforms.xls module and select the Income and Substitution Effects worksheet.  Then move the px control enough so you see two black dots distinctly.   You should also see two curves, one in pink the other in blue, and three straight lines, one in pink, one in orange, and one in blue.  These are all indicated in the legend.  

Now unprotect the sheet (it's ok if you've already done this) and right click on the graph itself.  That should bring up the following menu which has many of  the graph controls in it.

    

Click the Source Data item.  The click the Series tab.  That should bring up a window like

Drag this window out of the way (probably to the right) so that the actual graph is not covered up.  It is ok to cover the legend. Select the bottom most Series called Compensated Demand.  This actually plots the dot that is the tangency between the orange line and the pink curve.  Click the color button on the X Values line.  This will show you which cell is generating the X value for that series.  Click the color button again on the X values bar to return to the Series window.  Now click the color button on the Y Values line.  Later you can come back to this Window to explore other series.  For now, click OK to close the window.

Now that you see the linkage between the point in graph called Compensated Demand and the cells that generate that point, let's see how to move that point by changing the values in one or both of those cells.  Position your page so you can view the both of these cells and the point on the graph (for me this required a little scrolling to the right).  In the cell M35, which controls the X value of the point, type in a larger number than what is there and hit return. Try typing in 35 or something like that.  The point should move to the right.  Now type in 135 into the same cell.  The value is so big that the point moves off the screen.  Click undo enough times to return you to the original tangency position.  Now try typing a smaller value into the cell N35, which controls the Y value.  The point should move down.  If you type a negative value, the point moves off the screen.  Again, click undo enough times to return you to the original tangency position.  Now click the spinner repeatedly.  Observe that the values of these cells change, so the point moves.  Other values of the sheet also change.  In particular, the orange line moves, but remains tangent to the pink curve.

This is the essence of the animation.  The path of the particle is controlled by a formula.  Here is the full chain.  The spinner directly controls D44.  B44 then scales the value that is in D44.  B45 then updates based on the value of B44 (and the value in B38).  Both M35 and N35 have B45 as part of their formulas. This may seem convoluted. I hope the labeling in column A makes this plainer.  In economic terms, we are adjusting px, and both components of the compensated demand depend on px.  

Other graph controls: Color, Thickness, and Scaling

Now move your mouse pointer right on top of the Compensated Demand point.   That should bring up a Text Box with Series "Compensated Demand" ......  Now right click.  Then choose Format Data Series.  That will bring up a screen as below.

 

Excel will set defaults for the Marker style and the color both of the marker and the line between two points in the series.  This is one case where I don't like the Excel defaults for my purposes and so I  change this for my own purpose.  For me, particles must be circles.  For lines and curves, I try to hide the individual points and make the marker the smaller dash.  For the particle I make the Size of the marker a little bigger, 7 pt.  For lines and curves, the marker is set at its minimum size, 2 pt.  I make the marker color the same as the line color.  Most of my lines are solid and of maximum weight (to hide the markers).  You will note I have made the line colors the same for the old indifference curve and the old budget line.  Likewise, I have made the line colors the same for the new indifference curve and the new budget lines.  This tool allows us to use color to make visual identifications.  Excel won't do that by itself, but we can.  It would be good to develop an expertise about how to give out such visual clues.  

Click OK and then after returning to the spreadsheet put your mouse pointer over one of the numbers on the horizontal axis.  You should see a text box that says Value (X) axis.  Right click.  Here is the deal.  Excel as its default will scale a graph to the data plotted in the graph.  For static graphs, this is a really slick feature.  With the animation, however, the graph rescales as the data change values.  That kills the effect of the animation.  So you need to freeze the Scale.  After right clicking select Format Axis.  Then click the Scale tab.  That will bring up a window as below.

If the boxes are checked, the value will automatically adjust.  Unchecking the box fixes the value.  For a new graph that has not been edited by me, all the boxes are checked from Minimum to Value (Y) axis Crosses at.  (Is Microsoft helping to legitimatize ending a sentence in preposition?  What power they have!!).  One has to do a similar exercise for the Value (Y) axis, fixing the Scale there as well.  

Tip: One of the reasons why I like the Scatter (XY) graph is that it allows a Value axis for both X and Y and allows the different series to have different X ranges.  In contrast, at least in what I've tried, the area graph doesn't allow a value axis for the X axis and all series have to have the same range for the X axis.  I have found this limiting and hard to control.  That is why if you look at the Welfare Analysis sheet in the Supply and Demand module, the fill is achieved through lines rather than through a solid area.  In doing these type of plots, I would stick with the Scatter graph.  

There are other things to consider, but this is all the basics.  Enjoy.