Chapters 1 - 5 Flashcards
What is the gathering, displaying, and the summarizing of data?
data analysis
The laws of chance, in and out of the casino can describe what?
probability
What is the science of drawing conclusions from specific data, using a knowledge of probability?
statistical inference
What are a statisticians raw material?
data
What type of plot is this and what type of table is used to summarize the data?
dot plot and a frequency table.
In a frequency table, what are the three guidelines used for forming class intervals?
- use intervals of equal length with midpoints at the convenient round numbers
- for a small data set, use a small number of intervals
- for a large data set, use more intervals.
In a histogram what does each bar represent?
each bar covers an interval and is centered at the midpoint, the bars height of the number of data points in the interval.
Plotting the relative frequency histogram against the weight will look indentical except?
the vertical scale
Name the diagram?
stem-leaf
Any set of measurements has two important properties?
the central or typical value and the spread about that value.
We can go a long way with a little notation. Suppose we’re making a series of observations… n then we’d write?
X1, X2, X3, … Xn
As the values we observe. Thus n is the ______ number of data points, and X4 is the value of?
total
Is the value of the 4th data point
An _____ is a table of data:
array
The mean (or average) is represented by ___ and how is it obtained?
x with a dash over it.
by adding all the data and dividing by the number of observations.
What is the short hand for X1 + X2 + … Xn?
Σ
using the Greek capital letter for SIGMA, for summation
For the sum X1 + X2 + … + Xn. We say?
“The sum of X1 as i goes from 1 to n”.
The average, or mean, of a set of data X1 is?
see formula
The _____ is another kind of center: The midpoint of the data, like the ‘median strip’ in a road.
median
When calculating the median value in a even number of a data set, where there is no middle value. How do you determine the median value?
average the two centermost values
What is meant by the measure of spread?
understanding the central point of a data set and describing the data’s spread, or how far from the center the data tend to range.
What is interquatile range and how is it implemented?
A way to perform a spread
- put the data in numerical order
- divide the data into two equal high and low groups at the median
- find the median of the low group, this is the first quartile
- the median of the high group is the third quartile or Q3
Now the (IQR) is the distance (or difference between them)
What is a box and whiskers plot and what does it display?
it shows off the IQR. The box’s ends are the quartiles Q1 and Q3 the median is the line inside the box. S
True or False
A box and whiskers plot is good at showing the differences amoung groups?
True
The standard measure of spread is the _________?
standard deviation
unlike the IQR, which is based on medians, the std measures the spread from the mean.
What does this formula measure?
standard deviation
