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Calittlefield
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What is an element?
The entites on which data are collected
EX: Name on the cities in data

What is a variable?
A characteristic of interest for the elements
EX: Hi, Lo, Condition

What is an obersvation?
The set of measurements obtained for a particular element

Data Values=
# of variables X # of elements

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)

Nominal
Data are LABES OR NAMES used to identify an attribute of the element
A nonnumeric label or numeric code may be used

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

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

Categorical Data (Qualitative Data)
Labels or names used to identify an attribute of each element

Quantitative Data
 Data indicating how many or how much
  Discrete measuring how many
  Continous measuring how much
Always numeric

Observational Studies
No attempt to control or influence the variables of interest

Experimental Studies
Variables of interest of identified at different times, so they can see how each influences the outcome

Frequency Distribution
A tabular summary of data showing the frequency of items in each of several nonoverlapping classes

Relative Frequency
Frequency / total sample size

Clas Width=
Largest Data Value  Smallest Data Value / Number of Classes

Skewed Right
Longer tail to the right
Mean will be more than the median

Skewed Left
Longer tail to the left
Mean will be less than the median

Means
Sample mean =
Population mean=

Trimmed mean
Deleting a % of the smallest and largest values from a data set and then computing the mean of the reamaining values

Percentile formula
i= (p/100)n
 p= percentile
 n= sample size

Range=
Largest value  smallest value

Interquartile Range (IQR)
Q3Q1

The variance?
The average of the squared differences b/t each data value and the mean

Standard Deviation?
The positive square root of the variance

Correlation Coefficient
Can take on values between 1 and +1
The closer it is to 0, the weaker the relationship

Arthimetic operations are inappropiate for..
the nominal scale

Statistical studes in which researchers do not control variables of interest are..
observational studies

Gender is an example of _____ data..
Nominal

The measure of lovation which is the most likely to be influenced by extreme values n the data set is..
Mean

What is a measure of dispersion?
Interquartile range (IQR)

The descriptive measure of dispersion that is based on the concept of a deviation about the mean is?
The standard deviation

The numberical value of the standard deviation can never be..
Negative

The measure of dispersion which is not measured in the same units as the original data is the..
Variance

A numerical measure of linear association b/t two variables is the..
Covariance

The coefficient of correlation..
cannot be larger than 1

Data collected over several time periods are..
Time series data

