Educational Statistics: Activities of Statisticians. Major activities in statistics involve: design of experiments and surveys to test hypotheses exploration and visualization of sample data summary description of sample data modeling of uncertainty (e.g. flipping a coin)
Three Types of statistical methods:
Population vs Sample
Parameters and Statistics
Variable: any characteristic that can vary across individuals, groups, or objects. For example:
Later we will look at various types of variables.
Values: the numerical value of a particular realization of a variable.
For instance if the variable is weight and Mortimer weighs 147 lbs. Then the value of the variable for Mortimer is 147.
Make sure you can distinguish between variables and values
Sampling error: the difference between a sample statistic and its corresponding population parameter.
Two important types of distributions:
Distributions of test scores.
Distributions of weight, height, etc.
Distribution of GRE scores for ALL ASU graduate students.
Internal vs External Validity
Internal validity: concerned with whether the methods and procedures used in a study warrant the conclusions drawn from the study.
External validity: concerned with the extent to which the results obtained on a sample generalize to the target population.
Statistical procedures are the toolsof research.
There are several types (or methods) of research studies and the type of statistical procedure used will often vary from one type of research to another.
The correlational method of research.
The experimental method is used when the researchers wants to establish a cause and effect relationship.
A quasi-experiment is similar to a (true) experiment except that here the independent variable is not manipulated by the researcher.
For example, in studying the effects of sex on mathematics achievement a researcher compares boys and girls (the independent variable).
Types of measurement.
Types of measurement: nominal.
Types of measurement: ordinal.
age type of instruction achievement
test score group assignment motivation
class size size of print creativity
Discrete and Continuous variables
time of day sequence of events
side of building sex of investigator
age of school building current events
number of children school enrollment
size of family number of books
Grade Level College classification
Occupation Time on task