Chapter 3 (3.1-3.4): Descriptive Statistics and Analytics--Numerical Methods Flashcards
In addition to describing the shape of a distribution, we want to describe the data set’s central tendency. This includes what 3 things?
Mean, median, and mode
A measure of central tendency represents the ________ (or middle) of the data.
center
average of the population measurements
population mean
a number calculated from all the population measurements that describes some aspect of the population
population parameter
(all the numbers we calculate using population measurements is called (population) parameter)
a number calculated using the sample measurements that describes some aspect of the sample
sample statistic
(when we calculate mean, median, and mode using samples, this is called (sample) statistics)
What are the 3 measures of central tendency?
Mean, median, and mode
the average or expected value
mean
the value of the middle point of the ordered measurements
median (Md)
the most frequent value
mode (Mo)
What is the symbol for population mean? What about sample mean?
- the fancy M
(the population mean is the value to expect, on average, in the long-run) - the x with a line over it
(the sample mean is a point estimate of the population mean)
How do you calculate mean?
Add all numbers and then divide that total by total number of classes
Mean is also called what other two things (these words are interchangeable)?
- Average
- expected value
For median, if the number of measurements is (odd/even), the median is the middlemost measurement in the ordering.
For median, if the number of measurements is (odd/even), the median is the average of the two middlemost measurements in the ordering.
odd; even
What do you have to do before calculating median?
Arrange the numbers in numerical (increasing) order
T or F: Modes are the values that are observed “most typically”.
True
If there are two modes, the data is ________.
bimodal
(ex: 3,4,5,5,5,6,6,6,7,8,9… 5 and 6 are bimodal)
If there are more than two modes, the data is _________.
multimodal
(ex: 1,1,1,2,2,2,3,3,3)
When data are in classes, the class with the (highest/lowest) frequency is the modal class.
highest
(the tallest box in the histogram)
Mean, median, and mode are _________.
descriptives
What are the 13 descriptive statistics?
- Mean
- Median
- Mode
- Standard Error
- Standard Deviation
- Sample Variance
- Kurtosis
- Skewness
- Range
- Minimum
- Maximum
- Sum
- Count
If mean=median=mode, then the curve will be:
a. skewed to the right
b. symmetrical
c. skewed to the left
b. symmetrical
If mode < median < mean, then the curve will be:
a. skewed to the right
b. symmetrical
c. skewed to the left
a. skewed to the right
If mean < median < mode, then the data will be:
a. skewed to the right
b. symmetrical
c. skewed to the left
c. skewed to the left
T or F: A population parameter describes some aspect of the population and is a number calculated using all population measurements. Its point estimate is calculated from a sample of measurements rather than all the population measurements.
True