Chapter 2 - Statistics and APA Ethical Guidelines
scatter plot
A graph with points plotted to show a possible relationship between two sets of data.
frequency distribution
A summary chart, showing how frequently each of the various scores in a set of data occurs
central tendency
Attempt to mark the center of distribution (mean median mode)
range
Distance between highest and lowest scores in a set of data.
median
Middle number/central score
Extreme scores or outliers
One extreme score that doesn't fit with the rest
negatively skewed
a distribution that trails off to the left and includes a particularly low score
postively skewed
a distribution that trails off to the right and includes an extreme score
standard deviation
a measure of variability that describes an average distance of every score from the mean the square root of the variance
normal curve
a theoretical bell-shaped curve for which the area under the curve lying between any two z scores has been predetermined
sampling error
an error that occurs when a sample somehow does not represent the target population
mean
average
histograms
bar graphs
measures of variability
depicts diversity of the distribution (range, variance and standard deviation)
descriptive statistics
describes a set of data
inferential statistics
determines whether or not findings can be applied to the larger population from which the sample was selected
frequency polygons
line graphs
correlation
measures the relationship between 2 variables
mode
most frequently occurring score
-1
perfect/strong negative correlation
+1
perfect/strong positive correlation
correlation coefficient
ranges from -1 to +1
variance
standard deviation squared
percentiles
the distance of a score from 0
line of best fit/regression line
the line drawn through the scatter plot that minimizes the distance of all the points from the line
p value
the probability that the difference between the groups is due to chance
0
weakest/no correlation