Chapter15 Basic Data Analysis: Descriptive Statistics

Univariate Analysis Univariate procedures What is the scale level of the variable? Interval Scale: Mean, Standard deviation; z test, t test Ordinal Scale: Median, Range Nominal Scale: Mode, Frequency distribution, Chi- square test

Coding Data and the Data Code Book Data entry: refers to the creation of a computer file that holds the raw data taken from all of the questionnaires deemed suitable for analysis Data coding: refers to the identification of codes that pertain to the possible responses for each question on the questionnaire Data code book: identifies all of the variable names and code numbers associated with each possible response to each question that makes up the data set

Types of Statistical Analyses Used in Marketing Research Data Reduction Data reduction: the process of describing a data matrix by computing a small number of measures that characterize the data set Four functions of data reduction: Summarizes the data: total counts, means, %. Applies understandable conceptualizations: Mean, S.D. Communicates underlying patterns:Normal distribution, skewed distribution, factor analysis, cluster analysis, etc. Generalizes sample findings to the population

Types of Statistical Analyses Used in Marketing Research Statistical Analysis

Types of Statistical Analyses Used in Marketing Research Statistical Analysis Five types of statistical analysis: Descriptive analysis: used to describe the data set Inferential analysis: used to generate conclusions about the population’s characteristics based on the sample data Differences analysis: used to compare the mean of the responses of one group to that of another group Associative analysis: determines the strength and direction of relationships between two or more variables: ± r, cross-tab. Predictive analysis: allows one to make forecasts for future events

Understanding Data Via Descriptive Analysis Two sets of descriptive measures: Measures of central tendency: used to report a single piece of information that describes the most typical response to a question Measures of variability: used to reveal the typical difference between the values in a set of values: Frequency distribution, s, range.

Understanding Data Via Descriptive Analysis Measures of Central Tendency Mode: the value in a string of numbers that occurs most often Median: the value whose occurrence lies in the middle of a set of ordered values Mean: sometimes referred to as the “arithmetic mean”; the average value characterizing a set of numbers

Understanding Data Via Descriptive Analysis Measures of Variability Frequency distribution: reveals the number (percent) of occurrences of each number or set of numbers Range: identifies the maximum and minimum values in a set of numbers Standard deviation: indicates the degree of variation in a way that can be translated into a bell-shaped curve distribution

Understanding Data Via Descriptive Analysis Measures of Variability…cont.

When to Use a Particular Descriptive Measure