QR Flashcards
A population consists of _____, whereas a sample is a _____________.
all subjects under study; representative subgroup or subset of a population
A researcher is studying possible grade inflation at colleges in Illinois.
The population is:
all college students GPAs
A researcher is studying possible grade inflation at colleges in Illinois.
The sample is ____________.
the group of students GPAs which were actually included in the averages
A _______ sample, is obtained when every subject of the population has an equal chance
of being selected.
random
A ___________ sample is taken by numbering each member of the population and then
selecting every kth member, where k is some natural number.
systematic
A _______________- sample is obtained when a population is divided into groups where the members of each group have similar characteristics, and a certain number of members from each
group are chosen at random.
stratified
A_________ sample is obtained when an existing group of subjects that represent the
population is used for a sample.
cluster
The arithmetic mean, also known as the arithmetic average, is found by ___________.
adding the values of the data and dividing by the total number of values
To find the arrange the data in order from smallest to largest. If the number of data values is odd, it will be one value in the middle of the ordered list. If the number of data
values is even, it will be the arithmetic mean of two middle values.
median
The _______ is the mean of the smallest and largest values in a data set.
midrange
The __________ is the value that occurs most often in a data set. A data set can have multiples.
mode
A sample of a predetermined size is chosen from the population. Care is taken to choose the sample in such a way that every sample of that size is equally likely to be selected.
For example, a random sample can be chosen like this. First, each member of the population is assigned a different number. Then, a predetermined number of these assigned numbers is drawn at random using a computer program or a random number table. The members assigned to the numbers drawn are selected for the sample.
A random sample with this description is also called a simple random sample.
Random Sample
The members of the population are listed in some order. Then, every member (such as every member) is selected for the sample until a predetermined sample size is reached.
(The number is usually chosen to be greater than and small enough so that the predetermined sample size can be reached before the end of the list.)
Systematic Sample
The population is divided into groups, with each group made up of members that share some particular characteristic(s), such as an occupation. Then, a fixed number of members (but not all members) from each group are randomly selected for the sample.
Stratified Sample
The population is divided into groups that tend to exist naturally, such as cities in a state. Then, all members of some randomly chosen groups (but not all groups) are selected for the sample.
Cluster Sample
