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What are 3 reasons to use statistics?
- To make sense of large amounts of data
- To test hypothesis
- To make predictions
What is data?
Measurements, facts, and/or numbers
What is a dataset?
All the data collected for one study
What are data elements (or units of observation)?
Entities on which data are collected
What is a variable?
A characteristic of interest of the elements
What is an observation?
- Values of all variables for one element
- Set of measurements for one element
What are the 4 scales of measurement?
What are the characteristics of a nominal scale?
- Label or name is used
- Data do not suggest any particular order
- Example: YSU students are classified by college/school/class
What are the characteristics of an Ordinal scale?
- Non-numeric, but order or rank is meaningful
- Example: freshman, sophomore, junior, senior
What are the characteristics of an Interval scale?
- Ordered, numeric
- Equal and fixed distances between points on the measurement scale.
- Does not have a true zero
- Example: temperature scale, SAT scores
What are the characteristics of a Ratio scale?
- Ordered, numeric, with real zero
- Ratio of two values is meaningful
- Example: income, distance, price, quantity
What scales are used for qualitative data?
What scales are used for quantitative variables?
What is cross-sectional data?
- Collected at (approximately) same point in time
- Example: US imports measured in 2005 vs. China
What is time series data?
- Collected over several time periods
- Example: Weekly earnings of private nonfarm workers in 1982 dollars (accommodating inflation)
What are descriptive statistics?
- Summaries of data, which may be tabular, graphical, or numerical.
- Makes data easier to understand, more meaningful
What are tabular methods to display descriptive statistics?
- Frequency table (one variable)
- Crosstabulation (more than one variable)
What are the graphical methods ti dispaly descriptive statistics?
- Bar graph (qualitative or categorical variables)
- Histogram (quantitative variables)
- Scatter plot (two variables)
What is the purpose of Inferential Statistics?
Draw conclusions, make predictions, or infer something about the population (the whole from looking at the sample (the part)
What is the population?
Total category under consideration
What is the sample?
Subset of population for analysis
What is a parameter?
- Characteristic of population
- Example: population mean (greek u)
What is a statistic?
- Measure derived from sample data
- Example: sample mean (x bar)
What is the main difference between descriptive and inferential statistics?
Inferential is the process of using sample statistics to draw conclusions about population parameters. So, it's the interpretation from the descriptive statistics.
When do errors most commonly occur in statistics?
When collecting the data
What is a census?
Conducting a survey to collect data for the entire population
What is a sample survey?
Conducting a survey to collect data for the sample
What is data mining?
Methods for developing useful decision-making information from large databases