Unit 1 - Topic 3 Flashcards
Representing a Categorical Variable with Tables
What is a random sample?
When you choose a sample by rolling dice, choosing names from a hat, or other real randomly generated samples. Humans can’t do this well without the help of a calculator, cards, dice, or slips of paper.
What is Frequency?
It is how often an outcome occurs.
What is a frequency distribution?
It is a table or a chart that shows how often certain values or categories occur in a data set.
What is meant by relative frequency?
The proportion of time an outcome occurs (frequency/total). Can be expressed as a fraction, decimal, percent, or rate.
How do you calculate relative frequency?
Divide the frequency (also called count) by the total number of outcomes.
What is meant by cumulative frequency?
Add up the frequencies as you go. Suppose you are selling 25 pieces of candy. You sell 10 in the first hour, 5 in the second, 3 in the third, and 7 in the last hour. The cumulative frequency would be:
10 (first hour), 15 (first hour + second hour), 18 (sum of first 3 hours), 25 (sum of all 4 hours).
Make a guess as to what relative cumulative frequency is.
It is the Added up Percentages. An example is selling candy, 25 pieces sold overall…, with 10 in the first hour, 5 in the second, 3 in the third, and 7 in the fourth hour. We’d take the cumulative frequencies, 10, 15, 18, and 25, and divide them by the total giving cumulative percentages… .40, .60, .64, and 1.00. Relative cumulative frequencies always end at 100 percent.
What is a frequency table?
A frequency table gives the number of cases falling into each category.
What is a relative frequency table?
A relative frequency table gives the proportion of cases falling into each category.
In categorical data represented in frequency or relative frequency tables, which provide the same information as proportions?
Percentages, relative frequencies, and rates.
