test 1 Flashcards
Statistics
Study of variability
Variability
All things have differences, and statisticians look a these differences
2 branchs of AP stats
inferential and descriptive
descriptive stats
describe collected data using pictures or summaries like mean, median, range, etc…
inferential stats
look at data of sample and use it to tell about the population
compare descriptive and inferential stats
descriptive explains about data; inferential uses data of sample to tell about an entire population
data
any collected info., generally each little measurement
population
group of interest, can be big or small
sample
A subset of population, taken to make inferences about the population, calculate statistics from samples
compare population to sample
populations generally are large, samples are small subsets of population; take samples to make inferences about populations, use statistics to estimate parameters
compare data to statistics
data is the individual bits of info collected, summarize data by, ex. finding mean of a group of data,
mean of sample is statistic, if data is from each member of population, mean is parameter
compare data to parameters
data is the individual bits of collected info, summarize data by, ex. finding mean of a group of data,
mean of sample is statistic, summary of sample; if data is from each member of population, mean is parameter, summary of population
parameter
numerical summary of a population like mean, median, mode
stastistic
numerical summary of a sample like mean, median, mode
Curious about average wait time at Dunkin Donuts drive through: randomly sample cars and find the average wait time is 3.2 minutes. What is the population parameter, statistic, parameter of interest, data?
parameter is the true average wait time at that Dunkin Donuts, a number you don’t have and will never know. Statistic is 3.2 minutes, average of data collected. Parameter of interest= population parameter. Data is the wait time of each individual car, like “3.8 min, 2.2 min, 0.8 min.” Average of that data is statistic, and use that to make inference about the true parameter
Compare DATA-STATISTIC-PARAMETER using categorical example
words, put into groups, data are individual measures, statistics and parameters are summaries;
“taco, taco, pasta, taco, burger, burger, taco…” statistic: 42% of sample preferred tacos, and parameter: 42% of population preferred tacos
Compare DATA-STATISTIC-PARAMETER using quantitative example
numbers,
“45 sec, 64 sec, 32 sec, 68 sec,” raw data, statistic: average breath holding time in the sample was 52.4 sec, and parameter: average breath holding time in population was 52.4 sec
census
sample of entire population, info. from every member of population
does a census make sense?
census is ok for small populations, impossible for big populations
difference between a parameter and a statistic
both are number summarizing a larger gorup of numbers, parameter from population, statistic from sample
If I take a random sample of 20 hamburgers from FIVE GUYS and count the number of pickles on each of them… and one of them had 9 pickles, then the number 9 from that burger would be called?
a datum, or a data value
If I take a random sample of 20 hamburgers from FIVE GUYS and count the number of pickles on each of them… and the average number of pickles was 9.5, then 9.5 is considered a?
statistic (a summary of a sample)