A First Look at Statistics and Data Collection Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Areas of Business that Rely on Statistics Quality Control Product Planning Forecasting Yearly Reports Personnel Management Market Research Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Basic Definitions Descriptive Statistics: the collection and description of data Inferential Statistics: analyzing, decision making or estimation based on the data Population: the set of all possible measurements that is of interest Sample: the portion of the population from which information is gathered. Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Basic Definitions Simple Random Sample: a sample in which each item in the population has an equal chance of being selected. Census: the selection of all population items Parameter: a measure calculated from the population Statistic: a measure calculated from the sample Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Basic Definitions Discrete Data: data that contains only integers or counting numbers. Continuous Data: any value over a particular range is possible. Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Measurement for Numerical Data Nominal data are merely labels or assigned numbers. Ordinal data can be arranged in order such as worst to best or best to worst. Interval data can be arranged in order and the difference between numbers has meaning. Ratio data differ from interval data in that there is a definite zero point. Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Data Sources Primary data come from an original (primary) source and are collected with a specific research question in mind. Secondary data represent previously recorded data collected for another purpose or as part of a regularly scheduled data collection procedure. Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Random Sampling versus Nonrandom Sampling Random Sampling ensures that the sample obtain is representative of the population. Nonrandom Samples or nonprobability samples are generated using a deliberate selection procedure. Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Nonrandom Samples Convenience samples Judgement samples Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Advantages and Disadvantages of Random Sampling Advantages: –Can generalize beyond the sample Disadvantages: –Data may be difficult to obtain –Data may be expensive to collect Introduction to Business Statistics, 5e Kvanli/Guynes/Pavur (c)2000 South-Western College Publishing

Advantages and Disadvantages of Nonrandom Sampling Advantages –Data are more easily obtained. –May provide enough information to make a decision. –Data can be used as an informal base of knowledge in preparation for a later random sample. The primary disadvantage is that the information can not be generalized beyond the sample. Introduction to Business Statistics, 5e Kvanli/Guy nes/Pavur (c)2000 South- Western College Publishing