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Introduction to Studies, Experiments, and Simulations. Presentation 3.1. Collecting Data. Data answers questions Pharmaceuticals – Is this drug effective? Is this drug safe for use? Census Bureau – Population estimates, economic, agriculture statistics, etc. NASA – January 1986 and research
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Introduction to Studies, Experiments, and Simulations Presentation 3.1
Collecting Data • Data answers questions • Pharmaceuticals – Is this drug effective? Is this drug safe for use? • Census Bureau – Population estimates, economic, agriculture statistics, etc. • NASA – January 1986 and research • Gallup Polls – political polling, entertainment polling • Financial Institutions – Will this loan be paid back?
One of many definitions… • Statistics is a collection of procedures and principles for gathering data and analyzing information in order to help people make decisions. • In statistics, the questions we have are about a population.
Population • The population is the entire collection of objects or individuals about which information is desired. • Example: • If we want to determine the % of men on campus, the population is ALL the people on campus. • Example: • If we want to determine the percentage of men in the US, the population is ALL people in the US.
Can we obtain the population? • For the first example, the campus probably has the exact list of students on this campus so yes, the population can be obtained. • Then, there would be no need for a sample as you would have a census (every member in the population) • But, for the US, there is not an accurate list of all the people. Some people do not have homes, some people are in this country illegally, and people are constantly dying and being born.
Taking a Sample • If we can’t obtain the population (by conducting a census), we’ll look to obtain a sample (which is a subset of the population). Sample Population
Using the Sample • Now that a sample is obtained, the question is: • What kind of population should this have come from? • This summarizes the general process of collecting and using data, now some details…
Collecting Data • There are an infinite number of ways to go about collecting data, but only a few of these methods will produce reliable, quality data. • The analysis of data can only be as good and reliable as the data itself!
Collecting Data • Three overarching ways of gathering data: • Observational Study • Experiment • Simulation • In each of these methods you will be taking a sample in order to represent a population.
Observational Study • In an observational study, as the name suggests, you are simply observing individuals and measuring variables. • That is, you are NOT doing anything to, or manipulating, the individuals.
Experiment • In an experiment, you do manipulate variables. • In technical terms, you deliberately administer a treatment in order to observe the response to that treatment.
Simulation • Simulations are much rarer than observational studies and experiments • Simulations are run only when probabilities are known as fact. • Simulations are done using technology in order to facilitate a large number of repetitions
Collecting Data • This concludes this presentation.