CDS 501 Post Midterm 2

systematically assign numbers to object, persons, or events according to rules determined by the research design to determine the degree of difference 

• determine the extent of IV on DV
• allows us to examine sim/diff between measured events
• forms the basis of statistical analysis

nature of the numbers associated with the observation 

ex) examining a speech sound by nasality and transcription yields different types of data (rating scales, frequency counts) which correspond to levels of measurement

• form (usually numerical) in which measurements are collected and stored
• dictate the types of statistical analyses that can be applied

• analyzing qualitative data from observations to help make decisions about the hypothesis 
• branch of math where data is analyzed and interpreted

a number describing a population characteristic

ex) average weight of women -- based on gen pop, not sample

number describing a sample characteristic

• mean
• median
• mode

can always be applied to data

• Descriptive Statistics 
• Inferential Statistics

• involves tabulating, depicting, and describing data
• a specific feature or characteristic of a set of data is measured
• data summary used to organize data (visual description of the results)
• used in qualitative and quasi experimental studies 
• may use simple count data

• number of occurrences of the behavior
• used in small samples

tests that allow us to estimate/predict characteristics of a pop from knowledge of characteristic from the sample 

(make inferences to the gen pop)

applied to data dependent on its properties 

• Level 1: Nominal Level 
• Level 2: Ordinal Level 
• Level 3: Interval Level
• Level 4: Ratio Level

• Level 1 of Stevens Taxonomy 
• naming level 
• has no quantitative properties 
• allows us to classify groups, categories, behaviors, and events 
• assumed that groups don't overlap 

ex) male and female; may be numbered (male=1 and female=2) as a descriptor, but the number itself has no value

• Level 2 of Stevens Taxonomy
• to rank/order the levels of the variable being studied 
• imprecisely measured data 
• ranked highest to lowest, greatest to least, etc.
• not suitable for  statistical analysis 
• ex) the likert scale

• Level 3 of Stevens Taxonomy 
• meaningful difference between the numbers on the scale 
• intervals are equal in size 
• distance between intervals is known and fairly consistent 
• NO ABSOLUTE ZERO (zero does not mean the absence of something)
• may have a relative zero 
• ex) decibels -- zero decibels isn't the absence of sound, just the lowest sound a human can hear

• Level 4 of Stevens Taxonomy 
• highest level of measurement 
• same characteristics as interval level PLUS the presence of an absolute zero, ordered levels, equal distance between intervals 
• can compare points along a scale in absolute terms 
• continuous variables that have all the math properties

• modify data values to make data more symmetrical and suitable for statistical analysis 
• make variability more consistent across variables 
• make relationships more linear

*the most powerful statistical methods assume that the data are distributed normally, but most raw data isn't

data that are not suited for statistical analysis 

ex) percentages, fractions

• assumption on which parametric stat analysis is based 
• assumption of most powerful statistical methods 
• larger samples make distribution more normal
• bell shaped curve

• measures of central tendency 
• measures of variability

• measures of location (central tendency)
• measures of variability (range)
• measures of individual location

• does not need normal distribution
• does not assume that data reps a normal distribution 
• used on nominal and ordinal data

general shape of a distribution near the mean

• large SD
• low wide curve

normal distribution

• small SD
• high, narrow curve

analyze groups with normal distribution

• number of different categories: determine which category was most critical 
• range: determine variation between two sets of data

• visually communicate info
• record info compactly 
• give info of distributions and shapes