1Describe a dot plot:
Data numbers are listed in ascending order (don't repeat), line is drawn above them, place dots above numbers to represent the frequency of each data point
2Describe the stem and leaf plot:
*left column are stems (first # ex, 24, it would be 2)
*don't skip stemps, need to display data gaps if they exist
*leaf portion (right column) is the 2nd digit of the numebr (ex, 4 in 24) write out repeats (again in ascending order)
3Data set is aka
distribution
4Data has ____ and _____ has meaning.
Data has shape and shape has meaning
5How do we describe shape in statistics?
*peaks, symmetry (around the midpoint), skewness (told by the tail)
6What are four terms used to describe graphs in statistics?
*peaks
*symmetry
*midpoint
*outliers
7What does "spread" mean?
*range where most data falls
8What does "center" mean?
*midpoint
9What does "outliers" mean?
*data doesn't fit into the pattern
10Can a graph be symmetric and skewed at the same time?
No, it must be one or the other
11Skewness describes what?
*describes where the tail is (lowest distribution portion is)
12What adj are commonly used to described shape?
*hefty, strong
13What are histograms?
*bar graph that is divided into continuous intervals (categories)
14Describe components of histograms:
*vertical axis (frequency or relative frequency of each interval
*horizontal axis (scale for the variable being studied)
15What characteristic of graphs do histograms highlight?
*shape of the data
16What is a frequency polygon?
*like a histogram but no boxes
*use connect the dots :)
17How do you turn frequency into relative frequency?
*divide frequency by total data value
18What does a time series do?
Graph that pairs data with time
19Describe axis' for time series graph:
x-axis: units of time
y-axis: variable being studied
20Difference between histogram and time series graphs?
*histogram (looks at a variable from one point in time)
*time series (looks at a variable from a time range)
21What is percentile?
*percent of values in a distribution (data set) that are less than the specific data value being examined
22Distribution is aka
data set
23What is the index formula? What is it used for?
I= (percentile/100)(n+1)
used to calculate the number in the distribution set that represents the score of a specific percentile
ex) get 7, you would go to the 7th data point in the distribution to get your score value
24How to calculate index when it's not a solid number?
*use formula:
value from data set based on index + decimal of index value(difference between the second value and first)
ex) index 9.1
9th value is 35
10th value is 36
formula:
=35+0.1(36-35)
=35.1
25What are percentiles? simple terms :)
specific locations in distribution (at)
26Does it matter if the calculated index value isn't actually in the data set?
No, it does not :)
27What is a quartile?
*special percentiles that separate data into quarters
28Explain what 1st, 2nd, 3rd quartiles represent:
1st: 25th percentile
2nd: 50th percentile
3rd: 75th percentile
29What is the interquartile range (IQR)? What does it measure?
*difference between the first and third quartile (Q3-Q1)
*measures the spread of the middle half of data
30_____ measures the spread of a graphs middle half of data.
Interquartile range (IQR)
31What is the median method of calculating?
*find middle point of data (circle if odd value, find average between it and succeeding value if even data set)
*make sure data points are in numerical order
32The 2nd quartile is aka
The median of the data (midpoint)
33What are two ways to compute quartiles?
*index formula ((percentile/100)(n+1))
*or finding the median of entire data, then medians of each smaller quartile
34What can be used to identify outliers? Explain how it works...
*IQR (interquartile range, Q3-Q1)
*if outlier is more than 1.5x(IQR) it is an outlier
35True or False, when finding percentiles and quartiles by hand, you need to order the data values first (ascending order)?
True