Chapter 12 Flashcards
Nominal scale
Variables have no numerical value
Ordinal scale
Levels exhibit minimal quantitative distinctions
Levels of variable being studied from lowest to highest
Interval scale
Levels are equal in size
No absolute zero
Ratio scale
Variables have both equal intervals and absolute zero point that indicates the absence of variable being measured
Has absolute zero point that indicates a dance of variable being measured
Three basic ways to describe results between relationship variables
Comparing group percentages
Correlating scores of individuals on two variables
Comparing group means
When describing nominal results you..
Compare group percentages
What type of analysis do you use when you do not have two distinct groups
Correlating individual scores
Individuals are measured on two variables
When using ratio scales (like score of aggression) what type of analysis do you use to describe the results
Comparing group means
Frequency distribution
Indicates the number of individuals who receive each possible score on a variable
Ways to graph frequency distribution
Pie chart
Bar graph
Frequency polygon
Pie charts
Divide into slices that represent percentages
Useful when representing nominal scale information
What type of chart do you use when describing nominal information
Pie
Bar graph
Use a separate and distinct bar for each piece of information
Frequency polygons
Use a line to represent the distribution of frequencies of scores
Most useful when the data represent interval or ratio scales
What type of chart to use for interval or ratio scales
Frequency polygon
Histogram
Uses bars to display a frequency distribution for a quantitative variable
Scale values are continuous and show increasing amounts on a variable such as age, blood pressure, or stress
Descriptive statistics
Allows researchers to make precise statements about data
Two statistics are needed to describe data
One number used to describe central tendency
Another number used to describe variability (how widely distribution of scores is spread)
Centeral tendency
A statistic that tells us what the sample as a whole, or on average is like
What are the measures of centeral tendency
Mean
Median
Mode
Mean
Set of scores obtained by adding all the scores and dividing by the number of scores
When is a mean an appropriate indicator for centeral tendency
When scores are measured on an interval or ratio scale
Median
Score that divides the group in half (50% scoring above and 50% scoring below)
When is the median appropriate for describing centeral tendency
When scores are on an ordinal scale
Also useful for interval and ratio scales
Mode
Most frequent score
When is mode an appropriate measure for centeral tendency
If nominal scale is used
What are the best indicators for centeral tendency
Median or mode (because a few unusual scores bias the mean)
Ex-when measuring centeral tendency of family income-the mean can skew the results because of super high numbers and it would look like the average family makes more money than they actually do
Variability
A number that characterizes the amount of spread in a distribution of scores
Standard deviation
Measures the variability.
Symbolized by a
Indicates the average deviation of scores from the mean
Variance
Symbolized by s2
A measure of the variability of scores about a mean
When is the only time standard deviation is appropriate
When using interval and ratio scales
Range
Difference between the highest and lowest score
Ways to measure variability
Standard deviation
Variance
Range
How to show relationships between variables
Using a bar graph or a line graph
Levels of independent variable are shown on ____
X axis
Dependent variables are shown on the ___
Y axis
When are bar graphs used
When values on the x axis are nominal categories
When are line graphs used
When the values on the x axis are numeric
Correlation coefficient
Statistic that describes how strongly variables are related to each other
The Pearson product moment correlation coefficient is used when
Both variables have interval or ratio scale properties
What is the Pearson product moment correlation coefficient called
R value
What can r values range from
0.00 to +-1.00
It indicates both strength and direction
How to calculate Pearson r correlation coefficient
Obtain two scores-one on each variable
Scatter plot
When each pair of scores is plotted as a single point in a diagram
Restriction of range
Occurs when the individuals in your sample are very similar on the variable you are studying
Curvilinear relationship
One cannot use Pearson r values when there’s a curvilinear relationship
Effect size
Refers to strength of association between the variables
Regression equations
Calculations to predict a persons score on one variable when that persons score on another variable is already known
Y=a+bX
Y-score to predict
X-known score
A-constant
B-weighing adjustment factor that is multiplied by x
Criterion variable
Predicting a future variable
Predictor variable
Score on some other variable used to predict criterion variable
Multiple correlation
Combines number of predictor variables to increase the accuracy of prediction of a given criterion or outcome variable
Partial correlation
A technique that provides a way of statistically controlling third variables
It’s a correlation between two variables of interest
Structural equation modeling
Term to refer to set of techniques to examine models that specify a set of relationships among variables using quantitative nonexperimental methods
