Chapter 12 Flashcards
What are the 4 different scales of measurement?
nominal, ordinal, interval, and ratio scales.
What does the most appropriate statistical analysis and graph depend on?
depends on each variable’s scale of measurement.
What are the levels of a nominal scale? Example?
different categories or groups that have no intrinsic numerical properties.
Ex: two kinds of therapies for depression.
What is an ordinal scale? Example?
variables using an ordinal scale rank order the levels from lowest to highest (or least to most), but the intervals between each rank order are not equal.
a list of the top ten restaurants in halifax would use an ordinal scale.
What is an interval scale? Examples?
the distance between each level are equivalent in size.
Scores on an intelligence test.
Is there a meanigful zero point on interval scales?
no there are no meanigful zero points that indicate a total absence of the construct.
how do ratio scales contrast with interval scales? examples?
ratio scales have equal intervals in addition to a true zero point.
response time and age.
Is it easy to know precisely whether an ordinal or an interval scale is being used? Why or why not?
no.
Ex: we assume that asking people to rate their state of health on a 4-point likert scale uses an interval scale, when the points are labelled very good, good, fair, and poor. But it is difficult to claim that the difference between very good and good is the same as the difference beteeen fair and poor.
However, it is common practice to treat variables measured like this as an interval scale, because whe ordinal sclaes are averaged across many instances, they take properties similar to an interval scale.
Are the statistical procedures used to analyze data with interval and ratio variables identical?
yes. Importantly, data measured on interval and ratio scales can be summarized using an arithmetic average, or what is known as the mean. It is possible to provide a number that reflects the mean amount for these variables
what is the mean actually called?
an arithmetic average
What are variables measured on interval and ratio scales often referred to as? Why?
continuous variables because they represent an underlying continuum
What do we call variables using intrval and ratio sclaes? why?
continuous variables
they can be treated the same way statistically.
What is the first step a researcher should take in analyzing data? why?
exploring each variable separately. Doing so allows us to get a sense for what the data for each of our variables look like and also identify any possible errors that might have occurred during data collection.
What is a frequency distribution?
A representation of how often each score was observed, arranged from lowest to highest score.
What does a frequency distribution indicate?
the number of participants who recieve or select each possible score on the variable
What variables can you create a frequency distribution for?
variables using any scale of measurement.
What is an example of a frequency distribution I would be familiar with?
when professors present a graph showing ho many students got each score on an exam.
What do graphical representations of frequency distributions allow us to see?
what our data looks like at a glance. You can quickly see what scores are most common, which are infrequent, and the shape of the distribution. You can also tell us whether there are outliers.
What are outliers?
Scores that are very different from the rest of the scores in a dataset (i.e., much smaller or much larger); also known as extreme scores.
What might an outlier reflect?
may reflect a data entry error that can be corrected.
What are the types of graphs used to depict frequency distributions?
the bar graph, the pie chart, histogram.
What is a bar graph?
A graph using bars to depict frequencies of responses, percentages, or means in two or more groups.
What does a bar graph use? What are they commonly used for?
a separate and distinct bar for eahc piece of information.
used for comparing group means but can also be used for comparing percentages
What information goes on the X-axis for bar graphs? y-axis?
X = any categories
y = any values.