1.2 Graphical Representation of Sample Data Flashcards
What are the two main types of plots?
- Data plots
- Frequency plots
What are examples of data plots?
- Line chart (in time)
- 2D plots (in space)
- Biplot
- Scattergram
What are examples of frequency plots?
- Pie chart
- Bar chart
- Histogram
- Frequency polygon
- Frequency table
What is a discrete quantitative random variable?
When the number of its possible values is 1) infinite or 2) infinite and COUNTABLE (integers or fractions)
What is a continuous quantitative random variable?
When the number of its possible values is infinite and UNCOUNTABLE (real numbers)
What is the notation for random variables?
Capitals
What is the notation for observed values of random variables?
Small letters
What is a real number?
A real number includes irrational numbers (cannot be constructed from ratios)
Is this an example of a discrete or continuous quantitative random variable:
Counting the number of eggs a chicken lays.
Discrete quantitative random variable
Is this an example of a discrete or continuous quantitative random variable:
Counting the number of bacteria in a swamp.
Continuous quantitative random variable
Is this an example of a discrete or continuous quantitative random variable:
Weight, height, nitrogen content, speed of a car, cholesterol rate in blood
Continuous quantitative random variable
For a given random variable X, how would you illustrate the random sample of size n?
Xn
For a given random variable X, how would you illustrate the individual observation?
xn
What directs the drawing of frequency plots?
The nature of a random variable (qualitative, discrete quantitative, continuous quantitative)
What can be added up to n? What is n?
- Frequencies or counts
- n is the sample size
What do relative frequencies add up to?
1.0 or 100%
What is a random variable?
- Characteristic whose value varies among the individuals of a biological population
- Cannot be predetermined
Which main type of graphical representation requires at least two variables?
Frequency plots** verify with prof
What kind of plot would you use to collect observations sequentially in time?
Line chart (data plot)
What are two-dimensional (2D) plots used for?
To illustrated spacial data occurring along two axes
Give an example of discrete quantitative data in a 2D plot.
Abundance in a quadrant (e.g. trees)
Give an example of continuous quantitative data in a 2D plot.
Soil pH
What is a biplot or scattergram?
Individual observations for one random variable X are plotted against the observations on the SAME individuals for another random variable Y
What is the restriction of a scattergram?
- They are restricted in that each pair of observations is collected on the same individual
- They are NOT restricted to spatial data
How is relative frequency obtained?
By dividing the frequency by the sample size (n)
Are grades (100% scale) discrete or continuous quantitative?
Continuous quantitative, because we ASSUME that any mark between 0 and 100 is possible
What kind of data can a pie chart be used for?
- Qualitative
- Discrete quantitative
- Continuous quantitative
What kind of data can a bar chart be used for?
- Qualitative
- Discrete quantitative
- NOT for continuous quantitative
What kind of data can a histogram be used for?
Restricted to continuous quantitative random variables
What is a frequency polygon?
Successive histogram ordinates are connected at class midpoints
