QBA Exam 1
Statistics is how data goes from being a bunch of numbers to being?
procedures for organizing and summarizing data.
What can descriptive statistics tell us?
What scores did we obtain?
are the scores generally high or low?
are the scores close together?
how does any one score compare to the others?
Procedures used to infer about a large group of people or items based on data collected from a small subset of this group
complete set of events in which you are interested, usually quite big
Numerical values summarizing data population. Greek symbols
set of actual observations; subset of the population
numerical values summarizing sample data. english symbols
Why are population parameters difficult to calculate?
Cost prohibitions and the infeasibility of collecting data on the entire population
The teachers' union in California wants to know the average salary for high school teachers throughout the country. what is the teachers union presumably planning to calculate?
data that is collected over a period of time
data that is collected at the same point of time
properties of objects/people that can take on different values
ex. age, political attitudes, geographic region, etc.
data representing counts or numbers of observations in each category
ex. the # of males or females
data obtained by measuring objects or events
ex. height, weight, money, time
variables that can take on any value. allows for fractional amounts or decimals.
ex. weight, time, age
variables that can take on only a small set of possible values.
ex. number of traffic tickets, gender
are nominal variables discrete or continuous?
what is an example of a continuous quantitative variable?
Time spent commuting to work
assignment of numbers to data
numbers are used to distinguish among objects. the numbers have no meaning-- qualitative
ex. gender: male = 1, female= 2
numbers used to place objects in order along a continuum- rank order. No info about the differences between points on the scale, just info about relative order/rank
ex. your list of top 10 favorite movies
scale where equal intervals between objects represent equal differences. can speak of differences between scale points. no true zero point, and ratios are not equal.
ex. the difference between 80 degrees and 40 degrees = the difference between 120 degrees and 80 degrees
same as interval but with a true zero/absolute point.
ex. height, weight, calories consumed, time, friends
ratios ARE meaningful