Creating a Codebook

Definitions Case Variable Values

Type of variable (Numeric or String) Missing Values Elements of a Codebook Variable Names Type of variable (Numeric or String) Missing Values Levels of Measurement Nominal Ordinal Interval Ratio Dichotomy Codes

Rules for Variable Names in SPSS Variable Names may include letters and numbers, but they must begin with a letter. Do not use symbols (/ + - ) in variable names. There can be no spaces in variable names.

Types of Variables Numeric Variables may contain numbers only. Letters are not allowed. String Variables may contain letters and numbers. SPSS prefers numeric variables wherever possible. Except in cases with infinite possibilities (names), convert string variables to numeric variables.

Levels of Measurement Nominal The value serves mainly as a label or name. When we attach numeric values to nominal vales, we are using numbers as symbols.

Levels of Measurement Ordinal Rank Order Each category has a unique position relative to the other categories—one is higher or lower, larger or smaller—but we do not how how much larger or smaller one category is compared to another.

(Continuous Level Data) Interval Level Measurement Levels of Measurement (Continuous Level Data) Interval Level Measurement Distances of categories are defined in terms of fixed and equal units (thermometer). Allows us to study differences, but not proportionate magnitudes. (80 degrees is not twice as hot as forty degrees.) Can perform most mathematical functions.

Levels of Measurement Dichotomies A variable with only two possible categories or variables (Sex, True/False, Yes/No) Can be treated as nominal, ordinal or continuous depending on the situation.

The convention is to use 9 for a one column missing value Missing Values Missing Values designate either missing information (where someone did not provide an answer) or may indicate that a particular question was not asked of this particular case. There are two types of Missing Values: System missing (where a column is left blank) Coded missing values (where a particular code is designated to indicate a missing value.) The convention is to use 9 for a one column missing value

(Continuous Level Data) Ratio Level Measurement Levels of Measurement (Continuous Level Data) Ratio Level Measurement Has all the properties of the interval scale, but the zero point is inherently defined. Height, weight, distance Ratio comparisons can be made. Any mathematical manipulations appropriate for real numbers can be applied to ratio level numbers.

Codes SPSS prefers numeric variables wherever possible. Except in cases with infinite possibilities (names), convert string variables to numeric variables. When Items require coding, assign numbers instead of letters to the responses. Numbers simplify both data entry and analysis. When in doubt it is better to code more information than less. It is often difficult to go back and gather additional information. Record information in as much detail as possible. Don’t create groups (20-29, 30-39). SPSS will enable you to create categories later

Create your codebook ID #_____________ Qn1. Age:____________ Qn2. Gender:_____________ Qn3. Race:____________ Qn4. Degree Programme: ____________ Qn5. Year of Study:___________ Qn6. Do you live on campus? ________ Qn7. Favourite Colour:__________ Qn8. Are you colour-blind? __________ Qn9. Do you smoke?_________ Qn10. Do you do sports at least once a week?_______