observations that have been collected
collection of methods for planning studies and experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclustions based on the data.
complete collection of all elements to be studied. Complete because it includes all subjects to be studied.
collection of data from EVERY member of population
SUBCOLLECTION of members selected from a population
numerical measurement describing some characteristic of a POPULATION
numerical measurement describing some characteristic of a SAMPLE
consist of numbers representing counts or measurements
can be separated into different categories that are distinguished by some nonnumeric characteristic
result when # of possible values is either a finite number or a "countable" number
result from infinitely many possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions or jumps.
nominal level of measurement
characterized by data that consist of names, labels, or categories only. Cannot be arranged in an ordering scheme.
ordinal level of measurement
can be arranged in some order, but differences between data values either cannot be determined or are meaningless.
interval level of measurement
like ordinal, but difference between any 2 data values is meaningful.
ratio level of measurement
interval level with additional property that there is also a natural zero starting point.
voluntary response sample
respondents themselves decide whether to be included
observe and measure specific characteristics but don't MODIFY subjects
apply some TREATMENT and then proceed to observe its effects on the subjects (experimental units)
data are observed, measured, and collected
data collected from the past by going back in time
data collected in the future from groups sharing common factors
not able to distinguish among effects of different factors
when an untreated subject incorrectly believes that he/she is receiving a real treatment and reports an improvement in symptoms
subject doesn't know whether he/she is receiving a treatment or a placebo.
blinding occured at 2 levels
members from population are selected in such a way that each INDIVIDUAL MEMBER has and equal chance of being selected
simple random sample
n subjects are selected so that every possible sample of the same size n has the same chance of being chosen
selecting members from a population in a way that each member has a known chance of being selected.
select a starting point then select every kth (10th, 50th, etc) element in the population
use results that are easy to get
subdivide the population into at least 2 different subgroups so that subjects within same subgroup share same characteristics
divide population into sections then randomly select some of those clusters and then choose ALL members from selected clusters