Summer Vocab Flashcards
Learn it all for test
What is Statistics?
The study of variability.
What is variability?
Differences; how things differ.
What are 2 branches of AP Statistics?
Inferential and Descriptive.
What are DESCRIPTIVE STATS?
Statistics that are explained through descriptions (mean, median range, etc.).
What are INFERENTIAL STATS?
A sample of the bigger picture, such as the population.
Compare Descriptive and Inferential STATS
Descriptive tells you about the data, inference uses that data.
What is data?
Any collected information.
What is a population?
The group your interested in.
What is a sample?
A subset of a population, often taken to make inferences about the population.
Compare population to sample.
Samples make up a population.
Compare data to statistics.
Data is the individual information collected in a group. To summarize them, you find the mean of a group, which is the statistic.
Compare data to parameter.
Data is the individual information found in a group. To summarize them, find the mean in a population, which is the parameter.
What is a parameter?
A numerical summary of a population.
What is a statistic?
A numerical summary of a sample.
What is a census?
Like a sample of the entire population, you get information from every member of the population.
Does a census make sense?
A census is ok for small populations (like Mr. Nystrom’s students) but impossible if you want to survey “all US teens”.
What is the difference between a parameter and a statistic?
Parameters come from populations, and statistics come from samples.
What is the difference between a sample and a census?
With a sample, you get information from a small part of the population. In a census, you get info from the entire population. You can get a parameter from a census, but only a statistic from a sample.
What are random variables?
If you randomly choose people from a list, then their hair color, height, weight and any other data collected from them can be considered random variables.
What is the difference between
quantitative and categorical
variables?
Quantitative variables are numerical measures, like height and IQ. Categorical are categories, like eye color and music preference.
What is the difference between
quantitative and categorical data?
Quantitative data is always a number. Categorical data is always a word. (yes, no, maybe)
What is the difference between
discrete and continuous variables?
Discrete variables are whole numbers, while continuous variables go on, like 4.685…
What is a quantitative variable?
A quantitative variable is numerical.
What is a categorical variable?
A qualitative variable can be put in categories.
What do we sometimes call a categorical variable?
A qualitative variable.
What is quantitative data?
The actual numbers gathered from each subject.
What is categorical data?
The actual individual category from a subject.
What is a random sample?
A actually random sample, such as a dice roll, or paper from a hat.
What is frequency?
How often something comes up.
Data or datum?
Datum is singular, data is plural.
What is a frequency distribution?
A table/chart that shows how often certain values or categories occur in a data set.
What is meant by relative frequency?
The PERCENT of time something comes up (frequency ÷ total)
How do you find relative frequency?
Divide the frequency by the total.
What is cumulative frequency?
Adding the frequencies as you go. (Sell 25 pieces of candy; 10 first, 5 second, 4 third, and 6 fourth. That’s 10, 15, 19, 25)
What is relative cumulative frequency?
The added up PERCENTAGES.
What is the difference between a bar chart and a histogram?
Bar charts are for categorical data (bars don't touch) and histograms are for quantitative data (bars do touch).
What is the mean?
The old average that used to be calculated. It is the balancing point of the histogram.
What is the difference between a population mean and a sample mean?
A population mean is a parameter, and a sample mean is a statistic.
What symbols are used for the population mean and the sample mean?
Mu (p with cut top) for population mean, x-bar (x with bar overhead) for sample mean.
How can you think about the mean and median to remember the difference when looking at a histogram?
The mean is a balancing point of a histogram, and the median splits the area of the histogram in half.
What is the median?
The middle number, always splits the area in half (always found at (n+1)/2)
What is the mode?
The most common number, or the peaks of a histogram. Often used in categorical data.
When is the mode often used?
With categorical variables.
How are mean, median and mode positioned in a skewed left histogram?
How’d in that order from left to right (—>) mean-median-mode.
How are mean, median and mode positioned in a skewed right histogram?
Goes in the opposite order from right to left (
Who chased the tail?
The mean chases the tail (and outliers).
