chapter one

• collections of observations, information we collect from experiments or surveys

  data
• the science of planning studies and experiments

  statistics
• the complete collection of individuals to be studied

  population
• collection of data from every member of the population

  census
• sub collection of members selected from a population

  sample
• sample chosen by a method in which each member of the population is equally as likely to make up the sample

  simple random sampling
• choosing a sample based on what is convenient to you

  sample convenience
• subdivide the population into different subgroups, called strata, which share the same characteristics, the a simple random sample is drawn from each subgroup

  stratified sampling
• divide the population area into sections (clusters), then randomly select some of those clusters, choose all the numbers from those selected clusters

  cluster sampling
• select some stating point and then select every kth element in the population

  systematic sampling
• the respondents decide whether to be included

  voluntary response
• voluntary response is never reliable
• data consists of numbers representing counts or measurements

  quantitative (numerical) data
• data consists of names or labels that are not numbers

  qualitative (categorical) data
• data that is countable/finite

  discrete data
• data that is uncountable/infinite

  continuous data
• data that consists of names, labels, or categories

  nominal level of measurement
• data that can be arranged from smallest to largest, but cannot be subtracted

  ordinal level of measurement
• data where sorting and subtracting is possible but there is no zero starting point

  interval level of measurement
• data where sorting, subtracting, and dividing is possible, has a zero starting point

  ratio level of measurement
• a type of study where we observe data and draw conclusions

  observational study
• a type of study where we apply treatment and draw conclusions

  experimental study
• individuals being studied

  subjects
• what is measured on each experimental unit

  outcome/response
• the procedures applied to each experimental unit

  treatments
• a study in which the investigator assigns the treatments to the experimental units at random

  randomized experiment
• neither the investigators nor the subjects know who has been assigned to which treatment

  double blind experiment
• subjects are divided into blocks in such a way that the subjects in each block are the same or similar with regard to a variable that is related to the outcome of the experiment

  randomized block experiment
• use randomness to determine who gets the treatment, there is no restriction on which subjects may be assigned which treatment

  completely randomized experimental design
• in observations studies subjects choose their own treatments
• three types of cohort studies

  cross sectional, retrospective, prospective
• cross sectional experiments study present data
• retrospective experiments study past data
• prospective experiments study future data (estimate)
• in a case-control study, the case group has the disease of interest and the control group does not
• a numerical measurement describing some characteristics of a population

  parameter
• a numerical measurement describing some characteristics of a sample

  statistic
• a variable that is related to both the treatment and the outcome

  confounding variable
• a study that is conducted by a procedure that produces the correct result on average is said to be unbiased
• a study that is conducted by a procedure that tends to overestimate or underestimate the true value is said to be biased