STAXXXX_Notes_ExamOne

STAXXXX_Notes_ExamOne - Created by Dane McGuckian...

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Created by Dane McGuckian Statistics Exam One Notes Statistics is a collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting and drawing conclusions based on the data. It is the science of data. Statistical thinking involves applying rational thought and the science of statistics to critically assess data and inferences. In this course we will divide our study of statistics into two categories: Descriptive statistics, is where we will organize and summarize the data, and… Inferential statistics is where we use data to make predictions and decisions about a population based on information from a sample. s Descriptive statistics utilizes numerical and graphical methods to look for patterns in a data set, to summarize the information revealed in a data set and to present that information in a convenient form. s Inferential statistics utilizes sample data to make estimates, decisions, predictions or other generalizations about a larger set of data. Above, we mentioned the word population. Let’s define two important terms used in this course:
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Created by Dane McGuckian The population is the set of all measurements of interest to the investigator. Typically, there are too many experimental units in a population to consider every one. However, if we can examine every single one, we conduct what is called a census . A sample is a subset of measurements selected from the population of interest. Example 1: In a study of household incomes in a small town of 1000 households, one might conceivably obtain the income of every household. However, it is probably very expensive and time consuming to do this. Therefore, a better approach would be to obtain the data from a portion of the households (let’s say 125 households). In this scenario, the 1000 households are referred to as the population and the 125 households are referred to as a sample. A parameter is a numerical measurement describing some characteristic of a population and computed from all of the population measurements. For example, a population average (mean), the average obtained from every item in the population, is a parameter. A statistic is a numerical measurement describing some characteristic of a sample drawn from the population. The example below will illustrate these ideas. One way to remember where parameters and statistics come from is to notice that the letter P is the first letter of Population and Parameter and S is the first letter of Sample and Statistic. Example 2: In the household incomes example from above, the average (mean) income of all 1000 households is a parameter, whereas the average (mean) income of the 125 households is a statistic. Example 3
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STAXXXX_Notes_ExamOne - Created by Dane McGuckian...

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