Chapter 2 Flashcards
What is a stem and lead diagram?
10’s as y axis, then the next value (5 for 15) is going on the next row
What use does a stem and leaf diagram have?
it’s a quick display of the distribution of data
What is a frequency histogram?
basically the stem and leaf diagram, but as a bar graph. Freq on Y axis, score/value on the X axis
What is a relative frequency chart?
same as a frequency histogram, but the y axis shows the proportion fo the total sample (total freq = 1). Therefore it is always in the form of a fraction
What is a relative frequency histogram?
For this, the width of the bar shows the amount of data that is available e.g. a normal bar chart is clunky, and with sufficient data, the bars will look like a perfectly shaped curve. Still essentially a relative frequency chart
The area under the curve/ bars must always = 1
What is the formula for the Mean?
Total / N
Use the dodgy 3 symbol (Sigma) for adding up all the initial values
What is the sample mean?
X bar
sigma x (total of all numbers in sample x)
divided by n (lowercase)
What is the population mean?
μ = Sigma X / N (uppercase)
What is the median?
x͂
What effects does the distribution have on the mean and median?
when the distribution is symmetric, then the media and mean are likely to be the same
when the data is skewed right, with a lot of data points, the median reacts and moves more than the mean
What is the Mode?
most frequently occurring value
You can find this on the highest point on a relative frequency diagram
If lots of values are the highest and the same, then they are all the mode
What is a dot plots graph?
Bar graph, but dots as a measure instead of one collective block
What is the range?
Rmax - Rmin
What is the sample variance?
s^2 = Sigma (x-xbar)^2 all over n-1
What is the sample standard deviation?
just the square root of the sample variance (just s)
