Stats Chapter 1-2

Data

Information expressed as numbers

Rate

The number of actual occurrences of some phenomenon or trait divided by the number of possible occurrences per some unit of time. Usually multiplied by some power of 10

Ratio

The number of cases in one category divided by the number of cases in some other category

Proportion

The number of cases in one category of a variable divided by the number of cases in all categories of the variable

Midpoint

The point exactly halfway between the upper and lower limits of a class interval

Data Reduction

The process of using a few numbers to summarize many

Population

The total collection of all cases in which the researcher is interested

What are the four components of the wheel of science?

Theory, Hypotheses, Observations, Empirical Generalizations

Interval-Ratio

have actual numbers that can be analyzed with all possible statistical techniques

Nominal

have non-numerical "scores" or categories. Limited to comparing the relative sizes of the categories; must be mutually exclusive (no overlap between categories), exhaustive (place for every score), and categories should be similar

Ordinal

have scores or categories that can be ranked from high to low, so, in addition to classifying cases into categories, we can describe the categories in terms of more or less with respect to each other

Multivariate

Describes the relationship between more than two variables

Bivariate

Describes the relationship between two variables

What graphs are good for interval-ratio?

Histograms and line charts

Statistics

A set of mathematical techniques for organizing and analyzing data

Hypothesis

A specific statement, derived from a theory, about the relationship between variables

Percent Change

A statistic that expresses the magnitude of change in a variable from time 1 to time 2

Frequency Distribution

A table that displays the number of cases in each category of a variable

Independent Variable

A variable that is identified as a cause. Thought to cause the dependent variable

Dependent Variable

A variable that is identified as an effect or outcome. Thought to be caused by the Independent Variable

Cumulative Frequency

An optional column in a frequency distribution that displays the number of cases within an interval and all preceding intervals

Cumulative Percentage

An optional column in a frequency distribution that displays the percentage of cases within an interval and all preceding intervals

Variable

Any Trait that can change values from case to case

Research

Any process of gathering information systematically and carefully to answer questions or test theories. Statistics are useful for research projects that collect numerical information or data.

Sample

A carefully chosen subset of a population. In inferential statistics, information is gathered from one and then generalized to a population

Theory

A generalized explanation of the relationship between 2 or more variables

Line chart

A graph used for interval ratios

Histogram

A graph used for interval-ratio variables

Bar chart

A graph used for nominal and ordinal variables with only a few categories

Pie chart

A graph used for nominal and ordinal variables with only a few categories

Empirical Generalization

Made from trends in the data, might begin to develop ideas and observations when examining your original hypothesis

What graphs are good for any level of measurement? Mainly nominal and ordinal

Pie charts and bar charts

Quantitative Research

Research projects that collect data or information in the form of numbers

Measures of Association

Statistics that summarize the strength and direction of the relationship between variables; multivariate and bivariate

Univariate

Summarizes or describes the distribution of a single variable

Inferential Statistics

The branch of statistics concerned with making generalizations from samples to populations.

Descriptive Statistics

The branch of statistics concerned with summarizing the distribution of a single variable or measuring the relationship between two or more variables

Class interval

The categories used in the frequency distributions for interval-ratio variables

Stated Class Limits

The class intervals of a frequency distribution

Level of Measurement

The mathematical characteristic of a variable and the major criterion for selecting statistical techniques. Variables can be measured at any of 3 levels, each permitting certain mathematical operations and statistical techniques.

Level of Measurement

the mathematical nature of the variables under consideration