8-1 to 8-3 math quiz
Self-selected sampling
A sampling method made up of volunteers
systematic sampling
A procedure in which you start with one member chosen at random and then use a rule such as "every n'th unit is selected" to select members of the sample
statistical question
A question that has many different, or variable, answers.
experiment
A research method applying a treatment to some group or groups and measuring effects of treatment
stratified sampling
A type of probability sampling in which the population is divided into groups with similar characteristics and a random sample is chosen within each group
How do you find the mean?
Add all the numbers and divide by n
Students who are preparing for the junior class party want to determine what kinds of pizza to buy. They ask all the owners of the closest pizza restaurants what kinds of pizza they sell the most. What sampling method is this and is it biased?
Connivence sampling; biased, they are only choosing to ask pizza restaurants that are easy for them.
categorical variable
Data that falls into categories, or indicates a qualitative rather than a quantitive attribute
cluster sampling
Divide the population area into sections (or clusters). Then randomly select some of those clusters. Now choose all members from selected clusters.
How do you find the median?
If the numbers are odd, the center number is the median. If the numbers are even you take the two center numbers and add them and then divide by 2 to find the median.
What is the tallest mountain in the world? Is that a statistical question?
No, because there is only one correct answer to that question.
interquartile range
Q3-Q1
A video game store wants to discontinue one of the gaming consoles they sell, but want to ensure they keep the most popular. For two weeks the sales clerk asks every third customer which console is their favorite. Which type of study is described?
Sample
Statistical Variable
quantity or quality that can be measured or counted, and for which data are expected to differ from one observation to another
convience sample
sample chosen without any random mechanism; samples chosen based on ease of selection. like subjects that are in close proximity or are easy to get to
Population
set of all members of a group that you want to know about
If the mean is less than the median
skewed left
if the mean is greater than the median
skewed right
The graph looks the same on both sides
symmetric
Bias
systematically produces results that misrepresent a population
experimental group
the group in an experiment that receives the variable being tested
control group
the group that does not receive the experimental treatment.
What do you use to describe the data for distributions that are approximately normal.
use mean and standard deviation
What do you use for skewed distributions to describe the data
use median and quartiles to describe the data
simple random sample
every member of the population is equally likely to have a chance of selection and each possible sample of the size you want is each likely to be chosen
observational study
measures/observes members of a sample in a way they are not affected
What is the 5 number summary?
minimum, Q1, median, Q3, maximum
Quantitavie Variable
number data that can be compared, +,-, operated on
A company that manufactures light bulbs selects 3 bulbs at random. These bulbs are then tested to see how many hours they last. Which type of study is this?
observational
range of a data set
The difference of the greatest and least values in the data set.
What is the most popular clothing store amongst teenagers? Is that a statistical question?
Yes, because there can be many responses to that question.
Parameter
a measure that describes a characteristic of a population
statistic
a number that describes a sample of the population
Sample
a subset of the population that is being studied to answer a statistical question about the population
Sample Survey
asks every member of a sample the same set of questions and records the answers