Handling Data Flashcards
Once you have the class boundaries in a histogram, what do you need to work out?
Class width.
The area of a histogram represents what?
The frequency
What should you label the y axis in a histogram?
Frequency density
How do you find the frequency density when dealing with histograms?
Frequency divided by class width
What’s the first step to drawing a histogram from a table?
Find the class boundaries
How do you find the mean of a frequency histogram?
Find the midpoint of each bar
Multiply the midpoint by the height of the bar it came from
Add up the multiplied numbers
The divide by the total of all the heights of the bars
How do you find the mean of a density histogram?
Find the midpoint of each of the bars
Find the class length of the bar (e.i a bar from 10-15 would have a class length of 5)
Multiply the midpoint, class length and height of the bar.
Add these totals up for each bar
What are the two variable types in sampling?
Discrete and continuous
What is discrete data?
Data that can be classified into information
i.e hair colour
What is continuous data?
Data that can be measured on a scale
i.e someone’s height
In a random sample, how likely is everyone to be chosen?
Everyone has an equal chance
How do you find the sample size for each layer in stratified sampling?
The size of the whole sample divided by the size of the population, times the size of the layer
How do you find the angle for a pie chart when only given a table/graph?
The (number of/the total) x360
Eg. There’s 20 red cars in a car park of 180 cars. The angle in the pie chart would be 40.
How do you draw a frequency polygon?
Find the midpoint and plot it with the frequency
What is it very important to remember in a stem and leaf diagram?
A key
