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This document from Purdue University covers the concepts of types of data and sampling in statistics. It includes definitions, examples, and explanations of qualitative and quantitative variables, cross-sectional and time series data, and various sampling methods. Students will learn about the difference between probability and statistics, the types of variables and scales, and how to identify the type of variable for different examples.
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Sampling
Definitions Types of Data Sampling
STAT 225 Introduction to Probability Models April 16, 2104
Whitney Huang Purdue University
Types of Data, Sampling
Definitions Types of Data Sampling
Agenda
(^1) Definitions
(^2) Types of Data
(^3) Sampling
Notes
Notes
Sampling
Definitions Types of Data Sampling
Probability vs. Statistics
Figure : Taken from JHU Statistical Computing by Hongkai Ji
Types of Data, Sampling
Definitions Types of Data Sampling
Definitions
Statistics is the science of collecting, analyzing, presenting, and interpreting data Data set: all the data collected in a particular study Elements are the individual entities of a data set A variable is a characteristic of interest for the elements An observation is the set of measurements obtained for a particular element
Notes
Notes
Sampling
Definitions Types of Data Sampling
Example 61
Grade Major GPA Credit hours Sophomore Psychology 3. 14 30 Senior Spanish 2. 89 105 Senior Religion 3. 01 99 Freshman Philosophy 2. 45 12
(^1) How many elements are in the data set? (^2) How many variables are in the data set? (^3) What type of variable is each variable in the data set (be sure to answer both qualitative or quantitative as well as nominal, ordinal, interval, or ratio).
Types of Data, Sampling
Definitions Types of Data Sampling
Example 61 cont’d
Solution.
Notes
Notes
Sampling
Definitions Types of Data Sampling
Example 62
For this example, answer what type of variable each of the following are (^1) Smoking status (^2) Income (^3) Level of satisfaction (^4) clothing size (s, m, l, xl) (^5) time taken to run a mile
Types of Data, Sampling
Definitions Types of Data Sampling
Example 62 cont’d
Solution.
Notes
Notes
Sampling
Definitions Types of Data Sampling
Statistical Sampling
In Statistics, sampling is procedure to select a subset from a statistical population that is representative of the population. There are several types of sampling as follows: Simple random sampling (SRS): a sample selected such that each element in the population has the same probability of being selected Stratified random sample: elements in the population are first divided into groups and a simple random sample is then taken from each group
Types of Data, Sampling
Definitions Types of Data Sampling
Sampling cont’d
Probability sampling: elements in the population are selected with a known probability of being included in a sample Cluster sampling: the elements in the population are first divided into separate groups called clusters and then a simple random sample of the clusters is taken that all elements in a selected cluster are part of a sample Systematic sampling: randomly select one of the first k elements from the population and then every kth element thereafter is picked Convenience sampling: elements selected from the population on the basis of convenience Judgment sampling: elements are selected from the population based on the judgment of the person doing the study.
Notes
Notes
