Chapter 2

Question 1

What is a frequency distribution?

Answer 1

lists all possible data values or type, and the frequency of occurrence of each one

Essentially it counts how often something occurs

Question 2

What are the types of frequency distributions

Answer 2

• Ungrouped: Frequency of all possible data values in dataset; things that are already grouped
• Grouped: Applies when all “possible data values” would be too many so data is arranged and separated into groups called class intervals

• Groups: Need to bundle the data into chunks: i.e. Mass
• Each interval for grouped contains a range and the each set of data falls into one of the classes in the range
• Example of Ungrouped: Blood types, #of kids per family

Question 3

What type of values are required for grouped frequency?

Answer 3

Continous (need a range) but can be discrete (i.e. age)

Question 4

What does cumulative frequency mean in this example?

Answer 4

It represents how many people can do the preceding amount.

• If you can do 15, this means you can also do 14, 13, 12…

Question 5

What are the steps involved in Constructing a Frequency Distribution?

Answer 5

1. Count the number of scores
2. Identify the highest and lowest score in the data - Use MAX and MIN in Excel
3. Identify smallest unit of measurement - what was the smallest division possible used on the measuring scale
4. Decide on appropriate number of class intervals
5. Decide on score range of each class interval
6. Round the score range for class interval to make the range look prettier (WARNING: May be overlap)
7. List class intervals of scores in order

Question 6

Formula for deciding on score range for each class interval

Answer 6

i = largest score-smallest score/number of class intervals

Question 7

When listing class intervals of scores in order (step 7) what should you make sure the intervals have?

Answer 7

1. Same width (range of numbers)
2. No overlap across intervals
3. No gaps

Note: Begin with the smallest values for the smallest call interval bin

Question 8

When would you use ungrouped distributions?

Answer 8

1. Data are items; not numbers (Nominal or ordinal values)
2. Being able to use all possible data values without being too many

Question 9

When would you use grouped data for grouped distributions?

Answer 9

• Data values are continuous (i.e, weight, time, BP) or too many possible data values

Note: Good start would first estimate what would be a good number of intervals, but redo to get a nice looking class interval

Question 10

How do you correctly group grouped data?

Answer 10

1. Same width/range
2. No overlaps across bins
3. No gaps
4. Cover all the data in the set

Question 11

What are the two types of graphs used to plot frequency?

Answer 11

1. Bar Graphs - Grouped Data
2. Histograms - Ungrouped Data

Question 12

What do bar graphs help with? How are they structured?

Answer 12

• Depict frequencies or other group statistics
• Groups/categories are on the x-axis is nominal
• Separated with space between groups/categories

Bar graph with no space = histograms including interval/ratio data

Question 13

What type of graph is used to depict ungrouped frequency distributions?

Answer 13

Bar Graphs because ungrouped are nominal and ordinal (blood types, #of kids/family) which are easy to put the categories on the x-axis and the values on the y axis

Question 14

What type of graph is used to depict grouped frequency distributions?

Answer 14

Histograms because grouped requires intervals since the data is much bigger; put everything in ranges and compare them side by side with no space