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What is an element?
The entites on which data are collected
EX: Name on the cities in data
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What is a variable?
A characteristic of interest for the elements
EX: Hi, Lo, Condition
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What is an obersvation?
The set of measurements obtained for a particular element
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Data Values=
# of variables X # of elements
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Ordinal
The data have the properties of nominal data and the order or rank of the data is meangful
A nonnumeric label or numeric code may be used
EX: Freshmen(1), Sophomore(2), Junior(3), or Senior(4)
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Nominal
Data are LABES OR NAMES used to identify an attribute of the element
A nonnumeric label or numeric code may be used
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Interval
The data have the properties of ordinal data, and the interval between observations is expressed in terms of a fixed unit of measure
Melissa scored an 1885, Kevin scored a 1780, Melissa scored 105 points better than Kevin
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Ratio
The data have all the properties of interval data and the ratio of two is meaningful
Variables such as distance, height, weight, and time
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Categorical Data (Qualitative Data)
Labels or names used to identify an attribute of each element
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Quantitative Data
- Data indicating how many or how much
- - Discrete- measuring how many
- - Continous- measuring how much
Always numeric
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Observational Studies-
No attempt to control or influence the variables of interest
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Experimental Studies-
Variables of interest of identified at different times, so they can see how each influences the outcome
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Frequency Distribution-
A tabular summary of data showing the frequency of items in each of several non-overlapping classes
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Relative Frequency
Frequency / total sample size
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Clas Width=
Largest Data Value - Smallest Data Value / Number of Classes
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Skewed Right
Longer tail to the right
Mean will be more than the median
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Skewed Left
Longer tail to the left
Mean will be less than the median
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Means
Sample mean = 
Population mean=
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Trimmed mean
Deleting a % of the smallest and largest values from a data set and then computing the mean of the reamaining values
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Percentile formula
i= (p/100)n
- p= percentile
- n= sample size
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Range=
Largest value - smallest value
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Interquartile Range (IQR)
Q3-Q1
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The variance?
The average of the squared differences b/t each data value and the mean
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Standard Deviation?
The positive square root of the variance
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Correlation Coefficient
Can take on values between -1 and +1
The closer it is to 0, the weaker the relationship
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Arthimetic operations are inappropiate for..
the nominal scale
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Statistical studes in which researchers do not control variables of interest are..
observational studies
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Gender is an example of _____ data..
Nominal
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The measure of lovation which is the most likely to be influenced by extreme values n the data set is..
Mean
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What is a measure of dispersion?
Interquartile range (IQR)
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The descriptive measure of dispersion that is based on the concept of a deviation about the mean is?
The standard deviation
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The numberical value of the standard deviation can never be..
Negative
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The measure of dispersion which is not measured in the same units as the original data is the..
Variance
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A numerical measure of linear association b/t two variables is the..
Covariance
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The coefficient of correlation..
cannot be larger than 1
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Data collected over several time periods are..
Time series data
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