Texas Instruments TI-89 user guide: Other Modes that Affect a Split Screen

Other Modes that Affect a Split Screen

Split Screens and Pixel Coordinates

The TI-89 / TI-92 Plus has commands that use pixel coordinates to draw lines, circles, etc., on the Graph screen. The following charts show how the Split Screen and Split Screen Ratio mode settings affect the number of pixels available on the Graph screen.

TI-89:

TI-92 Plus:

Tip: For a list of drawing commands, refer to “Drawing on the Graph Screen” in Chapter 17.

Note: Due to the border that indicates the active application, split screens have a smaller displayable area than a full screen.

Exiting the Split Screen Mode

Method 1: Press [MODE] to display the MODE dialog box. Then set Split Screen = FULL. When you press [ENTER] to close the dialog box, the full-sized screen shows the application specified in Split 1 App.

Method 2: Press [2nd] [QUIT] twice to display a full-sized Home screen.

When You Turn Off the TI-89 / TI-92 Plus

Turning the TI-89 / TI-92 Plus off does not exit the split screen mode.

234 Chapter 14: Split Screens

Selecting the Active Application

With a split screen, only one of the two applications can be active at a time. You can easily switch between existing applications, or you can open a different application.

The Active Application

• The active application is indicated by a thick border.
• The toolbar and status line, which are always the full width of the display, are associated with the active application.
• For applications that have an entry line (such as the Home screen and Y= Editor), the entry line is the full width of the display only when that application is active.

Toolbar is for Y= Editor.

Thick border indicates the Y= Editor is active.

Entry line is full width when Y= Editor is active.

Switching between Applications

Press [2nd] [\square] (second function of [APPS]) to switch from one application to the other.

Tool bar is for Graph screen.

Thick border indicates the Graph screen is active.

Graph screen does not have an entry line.

Opening a Different Application

Method 1:

1. Use [2nd] [\square] to switch to the application you want to replace.
2. Use [APPS] or \blacklozenge (such as \blacklozenge [WINDOW]) to select the new application.

If you select an application that is already displayed, the TI-89 / TI-92 Plus switches to that application.

Method 2:

1. Press [MODE] and then [F2].
2. Change Split 1 App and/or Split 2 App.

If you set Split 1 App and Split 2 App to the same application, the TI-89 / TI-92 Plus exits the split screen mode and displays the application full screen.

Note: Also refer to "Using [2nd] [QUIT] to Display the Home Screen" on page 236.

Note: In two-graph mode, described in Chapter 12, the same application can be in both parts of a split screen.

Chapter 14: Split Screens 235

Using [2nd] [QUIT] to Display the Home Screen

Tip: Pressing [2nd] [QUIT] twice always exits the split screen mode.

When Using a Top-Bottom Split

Note: Both Top-Bottom and Left-Right splits use the same methods to select an application.

When you select a TOP-BOTTOM split, remember that the entry line and the toolbar are always associated with the active application. For example:

Entry line is for the active Y= Editor, not the Graph screen.

Toolbar is for the active Graph screen, not the Y= Editor.

236 Chapter 14: Split Screens

Data/Matrix Editor

15

• Preview of the Data/Matrix Editor ........ 238
• Overview of List, Data, and Matrix Variables ........ 239
• Starting a Data/Matrix Editor Session ........ 241
• Entering and Viewing Cell Values ........ 243
• Inserting and Deleting a Row, Column, or Cell ........ 246
• Defining a Column Header with an Expression ........ 248
• Using Shift and CumSum Functions in a Column Header ........ 250
• Sorting Columns ........ 251
• Saving a Copy of a List, Data, or Matrix Variable ........ 252

The Data/Matrix Editor serves two main purposes.

• This chapter describes how to use the Data/Matrix Editor to create and maintain a list, matrix, or data variable.

• Chapter 16 describes how to use the Data/Matrix Editor to perform statistical calculations and graph statistical plots.

Chapter 15: Data/Matrix Editor 237

Preview of the Data/Matrix Editor

Use the Data/Matrix Editor to create a one-column list variable. Then add a second column of information. Notice that the list variable (which can have only one column) is automatically converted into a data variable (which can have multiple columns).

Tip: If you don’t need to save the current variable, use it as a scratchpad. The next time you need a variable for temporary data, clear the current variable and re-use it. This lets you enter temporary data without creating a new variable each time, which uses up memory.

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Overview of List, Data, and Matrix Variables

To use the Data/Matrix Editor effectively, you must understand list, data, and matrix variables.

List Variable

A list is a series of items (numbers, expressions, or character strings) that may or may not be related. Each item is called an element. In the Data/Matrix Editor, a list variable:

• Is shown as a single column of elements, each in a separate cell.
• Must be continuous; blank or empty cells are not allowed within the list.
• Can have up to 999 elements.

Note: If you enter more than one column of elements in a list variable, it is converted automatically into a data variable.

Tip: After creating a list in the Data/Matrix Editor, you can use the list in any application (such as the Home screen).

On the Home screen (or anywhere else you can use a list), you can enter a list as a series of elements enclosed in braces { } and separated by commas.

Although you must use commas to separate elements on the entry line, spaces separate the elements in the history area.

To refer to a specified element in a list, use the format shown to the right.

Data Variable

A data variable is essentially a collection of lists that may or may not be related. In the Data/Matrix Editor, a data variable:

• Can have up to 99 columns.
• Can have up to 999 elements in each column. Depending on the kind of data, all columns may not have to be the same length.
• Must have continuous columns; blank or empty cells are not allowed within a column.

Note: For stat calculations, columns must have the same length.

Chapter 15: Data/Matrix Editor 239

Data Variable

(Continued)

From the Home screen or a program, you can use the NewData command to create a data variable that consists of existing lists.

Although you cannot directly display a data variable on the Home screen, you can display a specified column or element.

For example:

Displays column 1 of the variable data1.

Displays element 1 in column 1 of the variable data1.

Matrix Variable

A matrix is a rectangular array of elements. When you create a matrix in the Data/Matrix Editor, you must specify the number of rows and columns (although you can add or delete rows and columns later). In the Data/Matrix Editor, a matrix variable:

• Looks similar to a data variable, but all columns must have the same length.
• Is initially created with 0 in each cell. You can then enter the applicable value in place of 0.

Tip: After creating a matrix in the Data/Matrix Editor, you can use the matrix in any application (such as the Home screen).

Note: Use brackets to refer to a specific element in a matrix. For example, enter mat1[2,1] to access the 1st element in the 2nd row.

Shows the size of the matrix.

From the Home screen or a program, you can use \boxedSTO\blacktriangleright to store a matrix with either of the equivalent methods shown to the right.

Although you enter the matrix as shown above, it is pretty printed in the history area in traditional matrix form.

row 1 row 2

240 Chapter 15: Data/Matrix Editor

Starting a Data/Matrix Editor Session

Each time you start the Data/Matrix Editor, you can create a new variable, resume using the current variable (the variable that was displayed the last time you used the Data/Matrix Editor), or open an existing variable.

Creating a New Data, Matrix, or List Variable

1. Press \boxedAPPS and then select 6:Data/Matrix Editor.
2. Select 3:New.
3. Specify the applicable information for the new variable.

4. Press \boxedENTER (after typing in an input box such as Variable, press \boxedENTER twice) to create and display an empty variable in the Data/Matrix Editor.

Chapter 15: Data/Matrix Editor 241

Using the Current Variable

You can leave the Data/Matrix Editor and go to another application at any time. To return to the variable that was displayed when you left the Data/Matrix Editor, press [APPS] 6 and select 1:Current.

Creating a New Variable from the Data/Matrix Editor

From the Data/Matrix Editor:

1. Press [F1] and select 3:New.
2. Specify the type, folder, and variable name. For a matrix, also specify the number of rows and columns.

Opening Another Variable

You can open another variable at any time.

1. From the Data/Matrix Editor, press [F1] and select 1:Open. — or — From any application, press [APPS] 6 and select 2:Open.

Note: Variable shows the first existing variable in alphabetic order. If there are no existing variables, nothing is displayed.

2. Select the type, folder, and variable to open.
3. Press [ENTER].

Note about Deleting a Variable

Because all Data/Matrix Editor variables are saved automatically, you can accumulate quite a few variables, which take up memory.

To delete a variable, use the VAR-LINK screen ([2nd][VAR-LINK]). For information about VAR-LINK, refer to Chapter 21.

242 Chapter 15: Data/Matrix Editor

Entering and Viewing Cell Values

If you create a new variable, the Data/Matrix Editor is initially blank (for a list or data variable) or filled with zeros (for a matrix). If you open an existing variable, the values in that variable are displayed. You can then enter additional values or edit the existing ones.

The Data/Matrix Editor Screen

A blank Data/Matrix Editor screen is shown below. When the screen is displayed initially, the cursor highlights the cell at row 1, column 1.

Tip: Use the title cell at the very top of each column to identify the information in that column.

When values are entered, the entry line shows the full value of the highlighted cell.

Entering or Editing a Value in a Cell

You can enter any type of expression in a cell (number, variable, function, string, etc.).

1. Move the cursor to highlight the cell you want to enter or edit.
2. Press ENTER or F3 to move the cursor to the entry line.
3. Type a new value or edit the existing one.
4. Press ENTER to enter the value into the highlighted cell.

When you press ENTER, the cursor automatically moves to highlight the next cell so that you can continue entering or editing values. However, the variable type affects the direction that the cursor moves.

Tip: To enter a new value, you can start typing without pressing ENTER or F3 first. However, you must use ENTER or F3 to edit an existing value.

Note: To enter a value from the entry line, you can also use ▸ or ▴.

Chapter 15: Data/Matrix Editor 243

Scrolling through the Editor

When you scroll down/up, the header row remains at the top of the screen so that the column numbers are always visible. When you scroll right/left, the row numbers remain on the left side of the screen so that they are always visible.

How Rows and Columns Are Filled Automatically

When you enter a value in a cell, the cursor moves to the next cell. However, you can move the cursor to any cell and enter a value. If you leave gaps between cells, the TI-89 / TI-92 Plus handles the gaps automatically.

• In a list variable, a cell in the gap is undefined until you enter a value for the cell.

Note: If you enter more than one column of elements in a list variable, it is converted automatically into a data variable.

• In a data variable, gaps in a column are handled the same as a list. However, if you leave a gap between columns, that column is blank.

244 Chapter 15: Data/Matrix Editor

• In a matrix variable, when you enter a value in a cell outside the current boundaries, additional rows and/or columns are added automatically to the matrix to include the new cell. Other cells in the new rows and/or columns are filled with zeros.

Note: Although you specify the size of a matrix when you create it, you can easily add additional rows and/or columns.

Changing the Cell Width

The cell width affects how many characters are displayed in any cell. To change the cell width in the Data/Matrix Editor:

Tip: Remember, to see a number in full precision, you can always highlight the cell and look at the entry line.

1. To display the FORMATS dialog box, press F1 9 — or — TI-89: [♦] [1] TI-92 Plus: [♦] F

Cell width is the maximum number of characters that can be displayed in a cell.

All cells have the same cell width.

2. With the current Cell Width setting highlighted, press [◊] or [◊] to display a menu of digits (3 through 12).

3. Move the cursor to highlight a number and press [ENTER]. (For single-digit numbers, you can type the number and press [ENTER].)

4. Press [ENTER] to close the dialog box.

Clearing a Column or all Columns

This procedure erases the contents of a column. It does not delete the column.

Note: For a list or data variable, a clear column is empty. For a matrix, a clear column contains zeros.

To clear: Do this: A column 1. Move the cursor to any cell in the column. 2. TI-89: [2nd] [F6] TI-92 Plus: [F6] and select 5:Clear Column. (This item is not available for a matrix.) All columns Press [F1] and select 8:Clear Editor. When prompted for confirmation, press [ENTER] (or [ESC] to cancel).

Chapter 15: Data/Matrix Editor 245

Inserting and Deleting a Row, Column, or Cell

The general procedures for inserting and deleting a cell, row, or column are simple and straightforward. You can have up to 99 columns with up to 999 elements in each column.

Note About Column Titles and Headers You cannot delete the rows or cells that contain column titles or headers. Also, you cannot insert a row or cell before a column title or header.

Inserting a Row or Column The new row or column is inserted before the row or column that contains the highlighted cell. In the Data/Matrix Editor:

1. Move the cursor to any cell in the applicable row or column.
2. TI-89: [2nd] [F6] TI-92 Plus: [F6] and select 1:Insert.
3. Select either 2:row or 3:column.

Note: For a list variable, inserting a row is the same as inserting a cell.

When you insert a row:

• In a list or data variable, the row is undefined.
• In a matrix variable, the row is filled with zeros.

Note: For a list variable, you cannot insert a column because a list has only one column.

When you insert a column:

• In a data variable, the column is blank.
• In a matrix variable, the column is filled with zeros.

You can then enter values in the undefined or blank cells.

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Inserting a Cell

The new cell is inserted before the highlighted cell in the same column. (You cannot insert a cell into a locked column, which is defined by a function in the column header. Refer to page 248.) In the Data/Matrix Editor:

1. Move the cursor to the applicable cell.
2. TI-89: [2nd] [F6] TI-92 Plus: [F6] and select 1:Insert.
3. Select 1:cell.

Note: For a matrix variable, you cannot insert a cell because the matrix must retain a rectangular shape.

The inserted cell is undefined. You can then enter a value in the cell.

Deleting a Row or Column

In the Data/Matrix Editor:

1. Move the cursor to any cell in the row or column you want to delete.
2. TI-89: [2nd] [F6] TI-92 Plus: [F6] and select 2:Delete.
3. Select either 2:row or 3:column.

If you delete a row, any rows below the deleted row are shifted up. If you delete a column, any columns to the right of the deleted column are shifted left.

Deleting a Cell

In the Data/Matrix Editor:

1. Move the cursor to the cell you want to delete. (You cannot delete a cell in a locked column, which is defined by a function in the column header. Refer to page 248.)

Note: For a matrix variable, you cannot delete a cell because the matrix must retain a rectangular shape.

2. TI-89: [2nd] [F6] TI-92 Plus: [F6] and select 2:Delete.
3. Select 1:cell.

Any cells below the deleted cell are shifted up.

I f You Need to Add a New "Last" Row, Column, or Cell

You do not need to use the Util toolbar menu to:

• Add a new row or cell at the bottom of a column. — or — • Add a new column to the right of the last column.

Simply move the cursor to the applicable cell and enter a value.

Chapter 15: Data/Matrix Editor 247

Defining a Column Header with an Expression

For a list variable or a column in a data variable, you can enter a function in the column header that automatically generates a list of elements. In a data variable, you can also define one column in terms of another.

Entering a Header Definition

In the Data/Matrix Editor:

1. Move the cursor to any cell in the column and press F4. — or — Move the cursor to the header cell (c1, c2, etc.) and press ENTER.

Note: ENTER is not required if you want to type a new definition or replace the existing one. However, if you want to edit the existing definition, you must press ENTER.

Tip: To view an existing definition, press F4 or move the cursor to the header cell and look at the entry line.

2. Type the new expression, which replaces any existing definition.

If you used F4 or ENTER in Step 1, the cursor moved to the entry line and highlighted the existing definition, if any. You can also:

*Press CLEAR to clear the highlighted expression. Then type the new expression. — or — *Press ◄ or ► to remove the highlighting. Then edit the old expression.

Tip: To cancel any changes, press ESC before pressing ENTER.

You can use an expression that: For example: Generates a series of numbers. c1=seq(x^2,x,1,5) c1={1,2,3,4,5} Refers to another column. c2=2c1 c4=c1c2-sin(c3)

Note: The seq function is described in Appendix A.

Note: If you refer to an empty column, you will get an error message (unless Auto-calculate = OFF as described on page 249).

3. Press ENTER, , or ⨁ to save the definition and update the columns.

Note: For a data variable, header definitions are saved when you leave the Data/Matrix Editor. For a list variable, the definitions are not saved (only their resulting cell values).

You cannot directly change a locked cell (■) since it is defined by the column header.

Clearing a Header Definition

1. Move the cursor to any cell in the column and press F4. —or— Move the cursor to the header cell (c1, c2, etc.) and press ENTER.

2. Press CLEAR to clear the highlighted expression.

3. Press ENTER, ⨀, or ⨁.

248 Chapter 15: Data/Matrix Editor

Using an Existing List as a Column

Suppose you have one or more existing lists, and you want to use those existing lists as columns in a data variable.

Note: If you have a CBL 2™/CBL™ or CBR™, use these techniques for your collected lists.

\begin{tabular}{ll} \hline From the: & Do this: \ \hline Data/Matrix Editor & In the applicable column, use F4 to define the column header. Refer to the existing list variable. For example: c1=list1 \ Home screen or a program & Use the NewData command as described in Appendix A. For example: NewData datavar, list1 [, list2] [, list3] ... \newline Existing list variables to copy to columns in the data variable. \newline Data variable. If this data variable already exists, it will be redefined based on the specified lists. \ \hline \end{tabular}

Tip: Use 2nd [VAR-LINK] to see existing list variables.

To Fill a Matrix with a List

You cannot use the Data/Matrix Editor to fill a matrix with a list. However, you can use the list\blacktrianglerightmat command from the Home screen or a program. For information, refer to Appendix A.

The Auto-calculate Feature

For list and data variables, the Data/Matrix Editor has an Auto-calculate feature. By default, Auto-calculate = ON. Therefore, if you make a change that affects a header definition (or any column referenced in a header definition), all header definitions are recalculated automatically. For example:

• If you change a header definition, the new definition is applied automatically.
• If column 2's header is defined as c2=2*c1, any change you make in column 1 is automatically reflected in column 2.

Tip: You may want to set Auto-calculate = OFF to:

To turn Auto-calculate off and on from the Data/Matrix Editor:

1. Press F1 9 —or— TI-89: [◆] [1] TI-92 Plus: [◆] F
2. Change Auto-Calculate to OFF or ON.
3. Press [ENTER] to close the dialog box.

If Auto-calculate = OFF and you make changes as described above, the header definitions are not recalculated until you set Auto-calculate = ON.

Chapter 15: Data/Matrix Editor 249

Using Shift and CumSum Functions in a Column Header

When defining a column header, you can use the shift and cumSum functions as described below. These descriptions differ slightly from Appendix A. This section describes how to use the functions in the Data/Matrix Editor. Appendix A gives a more general description for the Home screen or a program.

Using the Shift Function

The shift function copies a base column and shifts it up or down by a specified number of elements. Use F4 to define a column header with the syntax:

shift (column [,integer])

Number of elements to shift (positive shifts up; negative shifts down). Default is -1. Column used as the base for the shift.

For example, for a two-element shift up and down:

c2=shift(c1,2) c3=shift(c1,-2)

Note: To enter "shift", type it from the keyboard or select it from the CATALOG.

\begin{tabular}{|l|l|l|} \hline c1 & c2 & c3 \ \hline 1 & 3 & undef \ 2 & 4 & undef \ 3 & undef & 1 \ 4 & undef & 2 \ \hline \end{tabular}

Shifted columns have the same length as the base column (c1). Last two elements of c1 shift down and out the bottom; undefined elements shift into the top. First two elements of c1 shift up and out the top; undefined elements shift into the bottom.

Using the CumSum Function

The cumSum function returns a cumulative sum of the elements in a base column. Use F4 to define a column header with the syntax:

cumSum (column)

Column used as the base for the cumulative sum

For example:

c2=cumSum(c1)

Note: To enter "cumSum", type it, select it from the CATALOG, or press 2nd [MATH] and select it from the List submenu.

250 Chapter 15: Data/Matrix Editor

Sorting Columns

After entering information in a data, list, or matrix variable, you can easily sort a specified column in numeric or alphabetical order. You can also sort all columns as a whole, based on a "key" column.

Sorting a Single Column

In the Data/Matrix Editor:

1. Move the cursor to any cell in the column.
2. TI-89: 2nd [F6] TI-92 Plus: [F6] and select 3:Sort Column.

Numbers are sorted in ascending order.

Character strings are sorted in alphabetical order.

Sorting All Columns Based on a “Key” Column

Consider a database structure in which each column along the same row contains related information (such as a student’s first name, last name, and test scores). In such a case, sorting only a single column would destroy the relationship between the columns.

Note: For a list variable, this is the same as sorting a single column.

In the Data/Matrix Editor:

1. Move the cursor to any cell in the “key” column.

In this example, move the cursor to the second column (c2) to sort by last name.

Note: This menu item is not available if any column is locked.

2. TI-89: 2nd [F6] TI-92 Plus: [F6] and select 4:Sort Col, adjust all.

When using this procedure for a data variable:

• All columns must have the same length.
• None of the columns can be locked (defined by a function in the column header). When the cursor is in a locked column, 📷 is shown at the beginning of the entry line.

Chapter 15: Data/Matrix Editor 251

Saving a Copy of a List, Data, or Matrix Variable

You can save a copy of a list, data, or matrix variable. You can also copy a list to a data variable, or you can select a column from a data variable and copy that column to a list.

Valid Copy Types

Note: A list is automatically converted to a data variable if you enter more than one column of information.

Procedure

From the Data/Matrix Editor:

1. Display the variable that you want to copy.
2. Press [F1] and select 2:Save Copy As.
3. In the dialog box:
   • Select the Type and Folder for the copy.
   • Type a variable name for the copy.
   • When available, select the column to copy from.

Note: If you type the name of an existing variable, its contents will be replaced.

Column is dimmed unless you copy a data column to a list. The column information is not used for other types of copies.

4. Press [ENTER] (after typing in an input box such as Variable, you must press [ENTER] twice).

To Copy a Data Column to a List

A data variable can have multiple columns, but a list variable can have only one column. Therefore, when copying from a data variable to a list, you must select the column that you want to copy.

List variable to copy to.

Data column that will be copied to the list. By default, this shows the column that contains the cursor.

252 Chapter 15: Data/Matrix Editor

Statistics and Data Plots

16

• Preview of Statistics and Data Plots ........ 254
• Overview of Steps in Statistical Analysis ........ 258
• Performing a Statistical Calculation ........ 259
• Statistical Calculation Types ........ 261
• Statistical Variables ........ 263
• Defining a Statistical Plot ........ 264
• Statistical Plot Types ........ 266
• Using the Y= Editor with Stat Plots ........ 268
• Graphing and Tracing a Defined Stat Plot ........ 269
• Using Frequencies and Categories ........ 270
• If You Have a CBL 2/CBL or CBR ........ 272

The Data/Matrix Editor serves two main purposes.

• As described previously in Chapter 15, the Data/Matrix Editor lets you create and maintain a list, matrix, or data variable.
• This chapter describes how to use the Data/Matrix Editor to perform statistical calculations and graph statistical plots.

Chapter 16: Statistics and Data Plots 253

Preview of Statistics and Data Plots

Based on a sample of seven cities, enter data that relates population to the number of buildings with more than 12 stories. Using Median-Median and linear regression calculations, find and plot equations to fit the data. For each regression equation, predict how many buildings of more than 12 stories you would expect in a city of 300,000 people.

254 Chapter 16: Statistics and Data Plots

Chapter 16: Statistics and Data Plots 255

15. Display the Y= Editor. For y1(x), the MedMed regression equation, set the display style to Dot.

Note: Depending on the previous contents of your Y= Editor, you may need to move the cursor to y1. PLOTS 1 at the top of the screen means that Plot 1 is selected. Notice that y1(x) and y2(x) were selected when the regression equations were stored. | \blacklozenge [Y=] [2nd] [F6] 2 | \blacklozenge [Y=] [F6] 2 | 16. Scroll up to highlight Plot 1.

The displayed shorthand definition is the same as on the Plot Setup screen. | \circlearrowleft | \circlearrowleft | 17. Use ZoomData to graph Plot 1 and the regression equations y1(x) and y2(x).

ZoomData examines the data for all selected stat plots and adjusts the viewing window to include all points. | [F2] 9 | [F2] 9 | 18. Return to the current session of the Data/Matrix Editor. | [APPS] 6 1 | [APPS] 6 1 | 19. Enter a title for column 3. Define column 3's header as the values predicted by the MedMed line.

To enter a title, the cursor must highlight the title cell at the very top of the column. [F4] lets you define a header from anywhere in a column. When the cursor is on a header cell, pressing [F4] is not required. | \circlearrowright \circlearrowleft \circlearrowright \circlearrowleft [2nd] [a-lock] M E D [alpha] [ENTER] [F4] Y 1 ( [alpha] C 1 [ ] [ENTER] | \circlearrowright \circlearrowright \circlearrowright \circlearrowright M E D [ENTER] [F4] Y 1 ( C 1 [ ] [ENTER] | 20. Enter a title for column 4. Define column 4's header as the residuals (difference between observed and predicted values) for MedMed. | \circlearrowright \circlearrowleft [2nd] [a-lock] R E S I D [alpha] [ENTER] [alpha] C 2 [-] [alpha] C 3 [ENTER] | \circlearrowright \circlearrowright R E S I D [ENTER] [F4] C 2 [-] C 3 [ENTER] | 21. Enter a title for column 5. Define column 5's header as the values predicted by the LinReg line. | \circlearrowright \circlearrowleft \circlearrowright [2nd] [a-lock] L I N [alpha] [ENTER] [F4] Y 2 ( [alpha] C 1 [ ] [ENTER] | \circlearrowright \circlearrowright L I N [ENTER] [F4] Y 2 ( C 1 [ ] [ENTER] |

256 Chapter 16: Statistics and Data Plots

22. Enter a title for column 6. Define column 6's header as the residuals for LinReg. TI-89 Keystrokes: \diamond \oslash [2nd] [a-lock] RESID [alpha] ENTER [F4] [alpha] C 2 \square [alpha] C 5 ENTER TI-92 Plus Keystrokes: \diamond \circ RESID ENTER [F4] C 2 \square C 5 ENTER Display:

23. Display the Plot Setup screen and deselect Plot 1. TI-89 Keystrokes: [F2] [F4] TI-92 Plus Keystrokes: [F2] [F4]

24. Highlight Plot 2 and define it as: Plot Type = Scatter Mark = Box x = C1 y = C4 (MedMed residuals) TI-89 Keystrokes: \diamond [F1] \diamond \diamond C [alpha] 1 \diamond [alpha] C 4 ENTER ENTER TI-92 Plus Keystrokes: \diamond [F1] \diamond \diamond C 1 \diamond C 4 ENTER ENTER Display:

25. Highlight Plot 3 and define it as: Plot Type = Scatter Mark = Plus x = C1 y = C6 (LinReg residuals) TI-89 Keystrokes: \diamond [F1] \diamond \diamond 3 \diamond C [alpha] 1 \diamond [alpha] C 6 ENTER ENTER TI-92 Plus Keystrokes: \diamond [F1] \diamond \diamond 3 \diamond C 1 \diamond C 6 ENTER ENTER Display:

26. Display the Y= Editor and turn all the y(x) functions off. From [F5], select 3:Functions Off, not 1:All Off. Plots 2 and 3 are still selected. TI-89 Keystrokes: \blacklozenge [Y=] [F5] 3 TI-92 Plus Keystrokes: \blacklozenge [Y=] [F5] 3 Display:

27. Use ZoomData to graph the residuals. \square marks the MedMed residuals; $+$ marks the LinReg residuals. TI-89 Keystrokes: [F2] 9 TI-92 Plus Keystrokes: [F2] 9 Display:

28. Display the Home screen. TI-89 Keystrokes: [HOME] TI-92 Plus Keystrokes: \blacklozenge [HOME]

29. Use the MedMed (y1(x)) and LinReg (y2(x)) regression equations to calculate values for x = 300 (300,000 population). The round function ([2nd] [MATH] 13) ensures that results show an integer number of buildings. After calculating the first result, edit the entry line to change y1 to y2. TI-89 Keystrokes: [2nd] [MATH] 1 3 Y 1 \square 3 0 0 \square \square 0 \square ENTER \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \leftarrow 2 ENTER TI-92 Plus Keystrokes: [2nd] [MATH] 1 3 Y 1 \square 3 0 0 \square \square 0 \square ENTER \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \diamond \leftarrow 2 ENTER Display:

Chapter 16: Statistics and Data Plots 257

Overview of Steps in Statistical Analysis

This section gives an overview of the steps used to perform a statistical calculation or graph a statistical plot. For detailed descriptions, refer to the following pages.

Calculating and Plotting Stat Data

Note: Refer to Chapter 15 for details on entering data in the Data/Matrix Editor.

Set Graph mode ([MODE]) to FUNCTION.

Enter stat data in the Data/Matrix Editor ([APPS] 6).

Perform stat calculations to find stat variables or fit data to a model ([F5]).

Tip: You can also use the Y= Editor to define and select stat plots and y(x) functions.

Define and select stat plots ([F2] and then [F1]).

Define the viewing window ([♦] [WINDOW]).

Tip: Use ZoomData to optimize the viewing window for stat plots. [F2] Zoom is available on the Y= Editor, Window Editor, and Graph screen.

Change the graph format if necessary. [F1] 9 — or — TI-89: [♦] [1] TI-92 Plus: [♦] F

Graph the selected stat plots and functions ([♦] [GRAPH]).

Exploring the Graphed Plots

From the Graph screen, you can:

• Display the coordinates of any pixel by using the free-moving cursor, or of a plotted point by tracing a plot.
• Use the [F2] Zoom toolbar menu to zoom in or out on a portion of the graph.
• Use the [F5] Math toolbar menu to analyze any function (but not plots) that may be graphed.

258 Chapter 16: Statistics and Data Plots