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NorthCrawfordStatCh1
The Nature of Probability and Statistics
Term | Definition |
---|---|
Statistics | The science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data. |
Variable | A characteristic or attribute that can assume different values. |
Descriptive statistics | Consists of the collection, organization, summarization, and presentation of data. |
Inferential statistics | Consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. |
Probability | The chance of an event occurring. |
Population | Consists of all subjects (human or otherwise) that are being studied. |
Sample | A group of subjects selected from a population. |
Hypothesis testing | A decision-making process for evaluating claims about population, based on information obtained from samples. |
Qualitative variables | Variables that can be placed into distinct categories, according to some characteristic or attribute. |
Quantitative variables | Numerical and can be ranked. |
Discrete variables | Values that can be counted. |
Continuous variables | Assume an infinite number of values between any two specific values. They are obtained by measuring. They often include fractions and decimals. |
Nominal level of measurement | Classifies data into mutually exclusive (nonoverlapping) categories in which no order or ranking can be imposed on the data. |
Ordinal level of measurement | Classifies data into categories that can be ranked; however, precise differences between the ranks do not exist. |
Interval level of measurement | Ranks data, and precise differences between units of measure do exist; however, there is no meaningful zero. |
Ratio level of measurement | Possesses all the characteristics of interval measurement and there exists a true zero. In addition, true ratios exist when the same variable is measured on two different members of the population. |
Random Samples | Selected by using chance methods or random numbers. |
Systematic samples | By numbering each subject of the population and then selecting every kth subject. |
Stratified samples | Divided the population into groups (called strata) according to some characteristic that is important to the study, then sampling from each group. |
Cluster samples | Population is divided into groups. |
Convenience sample | Researchers use subjects that are convenient. |
Observational study | The researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations. |
Experimental study | The researcher manipulates one of the variables and tries to determine how the manipulation influences other variables. |
Independent variable | An experimental study is the one that is being manipulated by the researcher. |
Explanatory variable | The independent variable is also called this. |
Dependent variable | The resultant variable. |
Outcome variable | Also called the dependent variable. |
Confounding variable | One that influences the dependent or the outcome variable but was not separated from the independent variable. |
Treatment group | The group that received the special instruction. |
Control group | Not the treatment group. |
Quasi-experimental study | Intact groups are used. |
Data | The values (measurements or observations0 that the variables can assume. |
Data set | A collection of data values. |
Data value (datum) | Each value in the data set. |