Chapter 1

collections of observations ( such as measurements, genders, survey responses)

the science of planning studies and experiments, obtaining data, and then organizing, summaraizing presenting, analyzing, interpreting, and drawing conclusions based on the data

the complete collection of all individuals (scores, people, measurements, and so on) to be studied; the collection is complete in the sense that it includes all of the individuals to be studied

collection of data from every member of a population

subcollection of members selected from a population

a numerical measurement describing some characteristics of a pupulation

a numerical measurement describing some characteristic of a sample

consists of numbers representing counts or measurements

consists of names or labels; categorical

discrete or continueous

• result when the number of possible values is either a finite number or a countable number
• (i.e. the number of possible values is 0,1,2,3,...)

Example: The number of eggs that a hen lays

result from infinitely many possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions, or jumps

characterized by data that consist of names, labels, or categories only, and the data cannot be arranged in an ordering scheme ( such as low to high)


Example: Survey responses yes, no, undecided

involves data that can be arranged in some order, but differences between data values either cannot be determined or are meaningless

Example: Course grades A, B, C, D, or F

like the ordinal level, with the additional property that the difference between any two data values is meaningful, however, there is no natural zero starting point ( where none of the quantity is present)

Example: Years 1000, 200, 1776

The interval level with the additional property that there is also a natural zero starting point ( where zero indicates that none of the quantity is present); for values at this level, differences and ratios are meaningful

Example: Prices of college textbooks (0$ represents no cost, a $100 book costs twice as much as a $50 book)

• Nominal- categories only
• Ordinal- categories with some order
• Interval- differences but no natural starting point
• Ratio- differences and a natural starting point

observing and measuring specific characteristics without attempting to modify the subjects being studied

apply some treatment and then observe its effects on the subjects; (subjects in experiments are called experimental units)

of n subjects selected in such a way that every possible sample of the same size n has the same chance of being chosen

select some starting point and then select every kth element in the population

use results that are easy to get

subdivide the pupulation in to atleast two different subgroups that share the same characteristics, then draw a sample from each subgroup

divide the pupulation area into sections (clusters); randomly select some of those clusters choose all members from selected clusters

collect data by using some comination of basic sampling methods

In multistage sample design, pollsters select a sample in different stages, and each stage might use different methods of sampling

data are obseved, measured, and collected at one point in time

data are collected from the past by going back in time ( examine records, interviews,...)

data are collected in the future from groups of sharing common factors ( called cohorts)

is used when subjects are assigned to different gropus through a process of random selection. THe logic is to use chance as a way to create two gropus that are similar

the repetition of an experiment on more than one subject

technique in which the subject doesn't know whether he or she is recieving a treatment or a placebo

blinding occurs at two levels:

• 1) the subject doesn't know whether he or she is receiving the treatment or a placebo
• 2) the experimenter does not know whether he or she is administering the treatment or the placebo

occurs in an experiment when the experimienter is not able to distinguish between the effects or different factors