Measures of Variability, Skewness, Kurtosis, & Graphical Charts Flashcards
Quantitatively measures how far apart the data points are or how they either scatter or cluster from the center
Measures of variability
It shows the average distance of a data point from the mean
Standard deviation
It is defined by the difference between the largest and the smallest measurements in the data set (Xmax - Xmin)
Range
What are the steps in calculating for the sample variance and standard deviation?
- sum of all squared differences
- divide by n-1
- get the square root
What are the steps in calculating for the population variance and standard deviation?
- sum of all squared differences
- divide by the population size
- get the square root
What are some basic measures of variability?
Range, variance, standard deviation
What does a negatively skewed (to the left) curve indicate
Mean < median
What is the skewness of a curve where its mean is greater than its median
Positively skewed (to the right)
Why isn’t the mean a better representation of the center in a skewed distribution of data?
Because it is sensitive to outliers/extreme values. the bigger the values, the bigger the mean
It measures the weight of the tails of the distribution
Kurtosis
What curve has zero kurtosis
Mesokurtic
It shows a curve in which most measures are at the tails
Leptokurtic (positive kurtosis)
It is when most measures are near the center of the distribution
Platykurtic (negative kurtosis)
What are the 5 main types of graphical charts?
Pie chart, bar chart/graph, column chart, line graph, scattered plot/dot chart
What are the steps in choosing charts for your data?
- Determine your message/the point you want to make
- Identify the comparison (component, item, time series, frequency distribution, or correlation)
- Select the chart form that corresponds with the type of comparison
