Quantitative Lecture 5 Flashcards
Describing and Graphing Data
What are the levels of data measurement?
Nominal, Ordinal, Interval, Ratio
What is nominal data?
Categorical data with no particular order to rank importance.
Examples include Gender (male, female, non-binary, other), Ethnicity (Asian, Black, White), Job Type (Managers, professional, etc.).
What is ordinal data?
Data that uses a scale to rank order but does not provide information about the distance between ranks.
Example: position in a race (1st, 2nd, 3rd).
What is interval data?
Data that is ordered with equal intervals between values but lacks an absolute zero.
Example: temperature (0°C does not mean no heat).
What is ratio data?
Data that has equal intervals and an absolute zero, allowing for meaningful ratios.
Examples include height and scores on an achievement test.
What are descriptive statistics?
Statistics used to describe and summarize data from a sample.
They summarize all levels of data and allow comparisons across studies.
What are inferential statistics?
Statistics that make inferences and generalizations about a population based on sample data.
Often require interval and ratio data.
What is the mean?
The sum of all scores divided by the number of scores in the sample.
Most commonly reported measure of central tendency.
What is the median?
The middle score when all scores are arranged in rank order.
Less commonly reported than the mean.
What is the mode?
The most frequently occurring score or category of scores.
Useful for categorical variables.
When are the mean, median, and mode identical?
They are identical when the distribution of the data is symmetrical and unimodal.
What is the population mean?
The typical score in a population.
Example: Population mean for IQ = 104.
What is sampling error?
The difference between the sample statistic and the population statistic.
What is a bar chart?
A graphical representation used to summarize a categorical variable.
X axis represents the categorical variable, Y axis represents frequency or percentages.
What is a histogram?
A type of bar chart for continuous variables, where bars are not separated and have equal width.
