LECTURE 2 Data Preparation SP110 STATISTICS FOR PSYCHOLOGY
OUTLINE Data Preparation Process Questionnaire Checking Editing Coding Transcribing Data Cleaning Statistically Adjusting the Data
DATA PREPARATION Enter the data ◦ Assign a number to each response item (planned when you design the questionnaire) ◦ Enter a clear code for missing values (no response), e.g. 99, 999, 999999 Make sure that your data set is complete and free of errors ◦ Some simple descriptive statistics (minimum, maximum, missing values, etc.) can help Learn how to document the data in your statistics program ◦ Enter labels for variables, labels for responses items, display instructions (e.g. decimal points to show) ◦ Define data-types (interval, ordinal or nominal) 3
Data Preparation Process 4 Prepare Preliminary Plan of Data Analysis Check Questionnaire Edit Code Transcribe Select Data Analysis Strategy Statistically Adjust the Data Clean
QUESTIONNAIRE CHECKING • The initial step in questionnaire checking involves a check of all questionnaires for completeness and interviewing quality. • A questionnaire returned from the field may be unacceptable for several reasons. 1. Parts of the questionnaire may be incomplete. 2. The pattern of responses may indicate that the respondent did not understand or follow instructions. 3. The responses show little variance. 4. One or more pages are missing. 5. The questionnaire is answered by someone who does not qualify for participation. 5
EDITING • Editing is the review of the questionnaires with the objective of increasing accuracy and precision. • It consists of screening questionnaires to identify illegible, incomplete, inconsistent, or ambiguous responses.
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- Fall '19
- Statistics, SPSS Data Editor