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What is measurement?
The assignment of numbers to some phenomenon that we are interested in analyzing

What is an operational definition?
a statement that describes how a concept will be measured

What is an indicator?
a variable or set of observations that results from applying the operational definition

What is an example of an operational definition?
Educational attainment for Head Start participants is defined by the achievement scores on the ITBS

What does this formula explain?
Indicator = concept + error
Indicators may not be a complete measure of a concept.

If numerous people accept an indicator as a valid indicator, then that indicator has ________ _________.
consensual validity

What does a reliable indicator do?
it consistently assigns the same number to some phenomenon that has not changed

What are the two major threats to measurement reliability?
 subjectivity (relies on the judgement of measurer or respondent)
 lack of precision

What is the difference between measuring validity and measuring reliability?
Reliability can be determined objectively (testtest reliability)

What is the most precise level of measurement?
interval level; based on a unit or interval that yields results in repeated application (ex. tons of garbage, response time in minutes)

What is special about ordinal levels of measurement?
It is possible to say that one unit of observation has more or less. (ex. very satisfied, satisfied, dissatisfied)

What is the difference of what Regression Analysis and what Contingency Tables are used for?
 Contingency tables are are used to analyze nominal and ordinallevel data
 Regression Analysis requires intervallevel data

What does a concept do?
It pinpoints an idea or element thought to be essential in accounting for the entire class

What causes a positive hypothesis?
If an increase (decrease) in the independent variable is thought to an increase (decrease) in the dependent variable

What is covariation?
The two variables move or vary together

What is "someone being able to predict the weather with feeling in their bones" an example of?
nonspuriousness

What is internal validity?
It addresses the question of whether, in a given study or research project, the independent variable did indeed cause or lead to changes in the dependent variable

What is external validity?
It concerns whether and to what extent results obtained in a given study can be inferred or generalized to hold true in settings, time periods, and populations different from the ones used in the study (ex. Are the results in the study applicable 20 years from now?)

What is the difference between quasiexperimental research designs and experimental design?
The ability of the researcher to control exposure to the experimental treatment or independent variable

What is a frequency distribution?
A table that pairs data valuesor range of data valueswith their frequency of occurence

What is the difference between the class frequency and the total frequency?
Class frequency is the number of observations of a variable within a particular class; total frequency is the total number of observations in the table

How do you perform a percentage distribution?
The frequency of each class should be divided by the total frequency for that case

What is a measure of central tendency?
a number of score or data value that represents the average in a group of data

Why is using the median sometimes better than using the mean?
An outlier has a much greater distorting effect on the mean than the median; when a phenomenon cannot be measured on an equal interval scale, the median is more helpful.

What is a measure of dispersion?
It tells how much the data do or do not cluster about the mean

What is the standard deviation?
the square root of the average squared deviation of the data from the mean; based on the squared differences between every item in a data set and the mean of that set

What is a z score?
the number of standard deviations a score of interest lies from the mean of the normal distribution

What is a chisquared test used for?
It measures statistical significance for relationships between variables measured at the nominal or ordinal level. It also assesses whether the relationship observed in a crosstabulation in a sample of data is sufficiently strong to infer that a relationship is likely to exist in the full populatuion

What does the chisquare test prove?
There is NO relationship between the two variables in the population and determines whether any apparent relationship obtained in a sample crosstabulation is attributable by chance

What are the degrees of freedom?
a number that gives some idea of the size of the empirical contingency table under study. You find it by multiplying one less than the number of columns Ex. (31)(31)= 4 degrees of freedom

What does the level of significance do?
It is the exact probability of error that he or she is willing to tolerate in making an inference from the sample crosstabulation to the parent population in the long run. Ex.

