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8 Cards in this Set
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 Back
∑

the operation of summation; the sum of all scores:
N ∑ X,i i=1 means "sum of the X variable from i = 1 to N" 

NOMINAL SCALE

lowest level of measurement, most often used with QUALITATIVE variables; the categories comprise the "units" of the scale
(e.g., brands of shoes, kinds of fruit, types of music) 

ORDINAL SCALE

a higher level of measurement than nominal: rand ordering the objects being measured according to whether they possess more, less, or the same amount of the variable being measured this says nothing of the magnitude of difference between the rankings
(e.g., a 400meter dash has a 1stplace, 2ndplace, and 3rdplace winner: the difference between 1st and 2nd may be small while the difference between 2nd and 3rd may be quite large) 

INTERVAL SCALE

measurement scale possessing the properties of magnitude *AND* equal interval between adjacent units but lacks an absolute zero point that is, the additional heat will cause the same change in temp no matter where on the scale the change occurs
(e.g., the Celsius scale of temperature; the difference in temperature between 51 and 52 is the same as the difference between 2 and 3 or 106 and 107) 

RATIO SCALE

all of the properties of the interval scale, but with an absolute zero point
(e.g., a reading of 0 on the Celsius scale of temperature corresponds to the temperature at which water freezes; a reading of 0 on the Kelvin scale corresponds to a complete absence of heat) 

CONTINUOUS VARIABLE

a variable that theoretically can have an infinite number of values between adjacent units on the scale
(e.g., weight, height, and time: you can be 190.22222222234 pounds) 

DISCRETE VARIABLE

variable in which there are no possible values between adjacent units on the scale
(e.g., number of children in a family, number of students in your class: there are 5 students in my cohort) 

REAL LIMITS OF A CONTINUOUS VARIABLE

those values that are above and below the recorded value by onehalf of the smallest measuring unit of the scale
(e.g., to record a [rounded] weight of 180 pounds, you must be over 179.5 but under 180.5) 