Chapter 15 Flashcards
Statistic
A numerical quantity that describes a sample
Parameter
A numerical quantity that describes a population
Descriptive statistics
The type of statistical analysis focused on describing, summarizing, or explaining a set of data
Graphical representations
Differentiate among the types of graphic representations of data and when they should be used
- Bar graph
- Histogram
- Line graph
- Scatterplot
Central tendency
Numerical value expressing what is typical of the values of a quantitative variable
Variability
Numerical value expressing how spread out or how much variation is present in the values of a quantitative variable
Relationships among variables
Determining whether independent and dependent variables are related
- They use independent (or predictor) variables to “explain variance” in dependent (or outcome) variables
Bar graphs
Graph that uses vertical bars to represent the data values of a categorical variable
- Display frequencies for a categorical variable
Histogram
Graph depicting frequencies and distribution of a quantitative variable
- Display frequencies across a variable that is quantitative
Line graph
A graph relying on the drawing of one or more lines connecting data points
- Highlights comparisons across one or more variables
Scatterplot
A graphical depiction of the relationship between two quantitative variables
Frequency distribution
Data arrangement in which the frequencies of each unique data value is shown
Mode
The most frequently occurring number
Median
The center point in an ordered set of numbers
Mean
The arithmetic average
Range
The highest number minus the lowest number
Variance
The average deviation of data values from their mean in squared units
- An index of how all values differ or diverge from the average score (mean)
Standard deviation
The square root of the variance
- Used as a comparison to evaluate how each score for the variables differ from the mean
Normal distribution
A theoretical distribution that follows the 68, 95, 99.7 percent rule
- Interprets scores in terms of how far they are from the mean using a normalized standard
- 68, 95, 99.7 percent rule: rule stating percentage of
cases falling within 1, 2, and 3 standard deviations
from the mean on a normal distribution
Z score
The values for a variable that have been transformed from their original “raw scores” into new “standardized” metric that has a mean of 0 and a standard deviation of 1
- A score that has been transformed into standard deviation units
Correlation coefficient
Index indicating the strength and direction of linear relationship between two quantitative variables
- Correlation describes the strength
- Coefficient indicated the +/-, which describes the direction of the linear relationship
Contingency table
Table used to examine the relationship between categorical variables
