Chapter 6 (Data Summary) Flashcards
What is categorical data?
Data values have values that correspond to categories or types.
What is anther name for categorical data?
Nominal, or qualitative
What is numerical data?
Data have integer or real number values.
What is anther name for numerical data?
Quantitative
What is the distribution of a variable?
The set of all values the variable can take in, and their associated probabilities.
What is a bar chart?
A chart that consists of bars with heights proportional to the number of observations in the category
What type of data do bar charts represent?
Categorical data
What are bar charts good for?
Comparing categories!
What does a pie chart emphasize?
The proportion of the total data set that falls into each category.
How to find the portion of a pie chart for a given category?
The angle will be r/n * 360 degrees
r = category value n = # of total observations
What data type do pie charts display?
Categorical
What is a histogram?
Similar to a bar chart, a histogram has bars, but is used to present numerical data, not categorical.
What is a smoothed histogram?
A curve that summarizes the features of a histogram.
How is data displayed in a histogram?
It is separated into “classes” or “bins”, and the count or percentage of the data in each class is represented by a bar.
What does plotting data enable us to do?
Look for overall patterns or deviations from the pattern in the data.
What are the extreme values (left and right ends) of a distribution called?
The tails
What is a skewed distribution?
A distribution with a long tail
What does a right skewed distribution look like?
The distribution has a long right tail
What does a left skewed distribution look like?
The distribution has a long left talk
What is a mode?
A peak in a distribution.
What is unimodal?
The distribution has one mode
What is bimodal?
The distribution has two modes.
What is multimodal?
A distribution with multiple modes in it.
What does a symmetric distribution look like?
It is the same in both of its tails. It can be flipped on the vertical axis in its middle.
What are outliers?
Observations that are apart from the majority of the data.
What to do when a data set has outliers?
Look for an explanation of the outliers. If they aren’t erroneous, do NOT remove them.
What is sample mean?
Sum of the values in a list divided by the number of values in the list.
What is the median?
The middle data point. If the number of observations is even, then the median is the mean of the two middle points.
What is the numerical mode?
The value that occurs the most often.
What is the pth percentile?
A value such that p% of the values are smaller than it
What is the lower quartile?
25th percentile
What is the interquartile range?
The difference between the upper and lower quartile.
What kind of data does a boxplot show?
Numerical data!
What does a boxplot look like?
- a central box between the upper and lower quartile
- a line through the box at the median
- “whiskers” extending to the minimum and maximum values.
