Chapter 1: statistical basis Flashcards
(52 cards)
statistics
the study of how to collect, organize, analyze, and interpret data collected from a group
- Has two branches
1. descriptive
2. inferential
descriptive statistics
collect and organize data
inferential statistics
analyze and interpret data
individual
person or object you are interested in finding out information about
variable (random variable)
the measurement or observation of the individual
population
-set of all the entire group of individuals about which we are interested
- collection of all outcomes, responses, measurements, or counts that are of interest
sample
a subset from the population, it looks just like the population, but contain less data
parameter
-a number calculated from the population. Usually denoted with a Greek letter
-this number is a fixed, unknown number that you want to find
statistic
-a number calculated from the sample. Usually denoted with letters from the Latin alphabet. Sometimes there is a Latin letter with a caret above it
-sometimes just put a bar over the letter
-used to estimate the parameter value
-a number that describes a sample characteristics
ex: average age of people from a sample of three states
- Ask yourself “is this fact about the whole population?”
-if there is a large population than most likely it is a statistic
parameter
-a number that describes a population characteristics
ex: average age of all people in the US
- Ask yourself “is this fact about the whole population?”
-if there is a small population than most likely it is a parameter
qualitative or categorical variable
- answer is a word or name that describes a quality of the individual
-consist of attributes, labels, or non-numerical entries
ex: major, favorite color, place of birth
quantitative or numerical variable
-answer is a number, something that can be counted or measured from the individual
ex: age, weight of a letter, temperature, time, distance
nominal
-data is just a name or a category
-there is no order and you can not do arithmetic
ex: gender, ethnicity, race, car name
ordinal
-data that is nominal, but you can put the data in order, since one value is more or less than another
-still cannot do arithmetic
ex: grades, place value in a race, size of a drink
interval
-data that is ordinal, but you can now subtract one value from another and it makes sense
-can do arithmetic but only adding and subtracting
ex: temperature, and time on a clock
Ratio
-data that is an interval, but you can now divide one value by another and that ratio makes sense
-you can do all arithmetic on this data
ex: height, weight, distance, time
counting numbers
-Integers, whole numbers, Natural numbers
- no in-between (fraction/decimal)
measuring numbers
- fractions, decimals, scientific notation
-for any two distinct (different) numbers, there is always one between
random variable
-represents a numerical value associated with each outcome of a probability distribution
-denoted by x
ex: x= hours spent on sales call in one day
discrete random variable
-has a finite or countable number of possible outcomes that can be listed
ex: number of sales calls a salesperson makes in one day
continuous random variable
-has an uncountable number of possible outcomes, represented by an interval on a number line
ex: hours spent on sales calls in one day
census
-not really a sample (try to measure all)
simple random sample
every different possible sample of size n has the same (equal) chance of being selected
stratified sample
divide into strata, randomly select some from each group
-seems like cluster sample but the strata are chosen specifically to represent different characteristics within the population
