spss17 statistics

8/8/2019 Spss17 Statistics

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MISSING DATA

Sometimes data is not available for a variety of reasons: the measuring instrument failed,a person neglected or refused to answer a question, the response is not applicable basedon the response to a previous question (e.g. 1. are you employed? y/n 2. does your job include benefits? y/n ). Sometimes a researcher wants to account for this data differentlyand be able to distinguish or account for the various reasons for the missing item.

If you do not need to account for the reason, the easiest thing to do is to leave that cellblank in the data entry sheet or in Excel. However, if you do know the various reasonswhy a number is missing, you might want to consider entering a code for it. Certainprocedures will treat all missing numbers the same; you can look at the frequencies totabulate the reasons. If you need to, you can recode missing values to the system missingvalue or to an interpolated value.

The easiest way to designate missing data is under Variable View.

Click in the appropriate cell in the Missing column.A button with 3 dots will appear to the right of the word "None". Click on it:

For numeric data, you can enter 3 discrete values or a range plus 1 optional discrete value.

Blank data will still be set to the System Missing value (will appear as a period in thedatasheet.

For string data, you are restricted to a maximum of 3 discrete values the "range" optionwill be greyed out and unavailable.

When you are done, click on OK.

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VALUE LABELS

Sometimes you want to associate a text string with your numeric data for instance, youmay have entered 1 for "blue" and 2 for "red".

The easiest way to create or modify value labels is under the Variable View tab:

Click in the appropriate cell under the Value column. Click on the button.

Enter a value and a label.

Click on the Add button.

When you are done, click on OK.

You can return here in the future and change value labels or remove them.

Intro to SPSS Statistics 17 Page 11


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MERGING DATA FILES

ADDING MORE OBSERVATIONS FROM ANOTHER FILE

If you wish to combine two data files with the same variables but

different cases, then choose Data > Merge Files > Add CasesChoose to merge two currently open datasets or browse to find a saved external data file:

Click on Continue

If a variable in the first active file is not part of the second file, click on the purple arrowbutton pointing to the right to include it in the new merged data set.

If there is the same variable in thetwo files but with different names, you can click on the variable from the external file andthen click on the Rename button. Supply the new name and click on the Continue button.

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Whether or not you rename the variable, you can manually pair variables that you knowmatch even though they might have different names:

1. Click on one variable on the left2. Hold down your Ctrl key3. Click on the second variable name so both names are now selected.

4. Click on the Pair button in the middle.

You can choose to create a new variable that will tell you which original data file the casescame from. The first file that was open will have 0's for the values; the second file selectedwill have 1's.

After all variable selections and pairs have been made, click on OK.

Your active file now includes data from the other file. If you wish the original active file toremain the same as before you started, then perform a File > Save As command to savethis current active dataset with a new name.



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AD D NEW VARIABLES FROM ANOTHER FILE

If the two data files have the same cases but include different variables,choose Data > Merge Files > Add Variables

Choose between an open dataset and an external SPSS .sav file.

Click on Browse to select the file (or select the open dataset).

Click on the Continue button.

Match Merge: 1. Check the box to match cases.2. Decide if you want unmatched cases from both files.3. Click on the variable name from the list of Excluded Variables4. Click on the purple arrow pointing in to the Key Variables box

5. You can choose to create a variable that tells which file the cases came from if youselected both files provide cases:

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COMPUTE NEW VARIABLES

1. Go to the Transform menu and select Compute Variable

2. Give the Target variable a name.

3. Click on the Type & Label button to verify or change the new variable's characteristics.

4. Create a numeric expression by choosing functions and variables and by entering orselecting numbers and symbols .

5. Click on the If button if you wish the computation to occur only for some cases



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DESCRIPTIVE STATISTICS

ANALYZE > REPORTS > CASE SUMMARIES

Select a variable from the list on the left and click on the purple arrow button to move itsname to the right (or double click on the variable name). SPSS is going to summarizethose variables listed in the variables box on the right. Repeat for additional variables.

You can choose to not display the actual cases or you can limit how many cases aredisplayed.

You can select one or more grouping variables.

Click on the Statistics button to request additional information to be displayed. Select adesired statistic from the list on the left and click on the purple arrow (or double click)

Click on Continue to return to the previous dialog.

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Click on the Options button to control the appearance of the output.


Click on OK to generate the report.



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ANALYZE > DESCRIPTIVE STATISTICS > FREQUENCIES

Use this for categorical data when you want 1-way frequencies and percentages.

Select a variable from the list on the left and click on the arrow button to move its name tothe right. SPSS is going to summarize those variables listed in the box on the right.Repeat for additional variables.

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Click on the Statistics, Charts, and/or Format buttons to request additional results or tocontrol the output appearance.



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Click on OK when you are ready to generate the Frequencies report.

Results will look something like:

ANALYZE > DESCRIPTIVE STATISTICS > DESCRIPTIVES

Use this when you have continuous variables. You select variables by clicking on theirnames on the left and then clicking on the arrow button in the middle.

If you want something other than the default results, click on the Options button.

Click on Continue to return to the Descriptives dialog.



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Click on OK to run the descriptives report.

Descriptives Results look something like:

ANALYZE > DESCRIPTIVE STATISTICS > CROSSTABS

Use this procedure when you want to look at 2-way frequencies of your categorical data.

Specify a row variable and a column variable.

Click on the Statistics button if you want Chi Squares or other statistics computed.

Click on the Cells button if you want to display percentages, expected cell counts, or otherinformation in addition to frequency counts.

Click on OK when you are ready to generate your results.

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INFERENTIAL STATISTICS

Analyze > Compare Means >

Independent-Samples T Test

Use this test when you have 2 independent samples and want to compare the means. Donot use this test when you have a pre-test / post-test situation.

Specify one or more dependent test variables for the top right box.

Specify one grouping variable. Ideally it should just have 2 values (you inflate your errorrate if you keep repeating this test for pairs of groups B use 1-way ANOVA if you haveseveral groups).

Click on the Define Groups button and specify the valid values for this grouping variable.



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OUTPUT VIEWER

When you run procedures from the Analyze or Graphs menu, you will automatically betaken to the SPSS Output Viewer. In the left frame, you will see a list of variousprocedures with their subordinate objects. More recent results appear at the bottom. Youcan use this left frame to navigate to previous results: click on the object name on the leftand it will appear in the frame on the right, with a thin black indicator box and a red arrow.

To collapse a procedure, click on the - sign to the left of its name. To see the list of its objects under a procedure, click on the + sign to the left of its name. To delete a portion of your results, click on the procedure name on the left and press

the Delete key. To see the associated notes for a procedure, double click on the Notes object name

listed beneath a procedure. To rename an item on the left, click in the box and type.

To change text on the right, double click on on the text box and type.

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SPSS STATISTICS 17 MENUS


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SPSS STATISTICS 17 TOOLBARS

DATA EDITOR STANDARD TOOLBAR

Open Print Undo / RedoGo to

Variable FindInsert

VariableWeightCases

Save DialogRecall

Go toCase

Variables InsertCase

Split File SelectCase

OUTPUT VIEWER STANDARD TOOLBAR

Open Print Export Undo / RedoGo toCase Variables

Show AllVariables

SavePrint

PreviewDialogRecall

Go toData

Go toVariable

UseVariableSets

SeleLastOutp

You can hide or view toolbars or choose to display larger buttons: View > Toolbars > Customize

The View menu also allows you to select a different fontwhether or not to display grid lines whether or not to display value labenot to display the status bar.

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