Descriptive Statistics

Upon successful data collection, what tasks could you do that would fall under the category of descriptive statistics?

• Describing and summarizing data

• Describing and annotating data

• Collecting and summarizing data

• Selecting and describing data

When we use grouped frequencies to display our data - we can use Ross or Hinkle conventions. Which statement is INCORRECT?

• The Ross convention is left end inclusive only

• The Hinkle convention uses an explicit midpoint

• The Ross convention will result in a loss of precision due to the width of class interval

• The Hinkle convention is right end inclusive only

Which statement is CORRECT while considering your class interval?

• A too narrow class interval can result in a loss of precision

• A too wide class interval can result in a loss of distribution pattern

• A too narrow class interval can result in sparse data collection

• A too wide class interval can result in empty intervals

We learned some shapes of frequency distributions. Which statement is INCORRECT?

• Most variables in the world follow the normal distribution.

• The uniform distribution has the same frequency for every value

• The bimodal distribution shows that you have encountered sub-populations

• The platycurtic distribution shows a low variance

Outliers can be found by computing the quartiles, and interquartile range (IQR). Specifically, an outlier is any value higher than the Reasonable Upper Boundary which can be computed by X*IQR. What is X?

• 1

• 1.5

• 3

• 2

Suppose a student has 3 scores: 68 in math, 77 in physics, and 83 in history. In which class did the student perform best?

• Physics

• Math

• History

• It depends....

Which of these are NOT a property of the standard z-score?

• Mean = 1

• Variance = 1

• Standard Deviation = 1

• Measures data in units of standard deviations

Based on this scatterplot, what can be said about the relationship between X and Y?

• The relationship is positively correlated

• The relationship is negatively correlated

• The correlation is weak

• The correlation is approximately 0.5

Take a closer look at this scatterplot, what can be inferred about X and Y?

• A high X will cause Y to also be high

• A high Y will cause X to also be high

• The value of X is strongly correlated to the value of Y

• The value of X is not correlated to the value of Y

How can we measure correlations numerically?

• Using a scatterplot

• Using the Pearson r

• Using the Spearman r

• Using the Pearson rho