MMW

Flashcards for vocabulary review

Data

Raw information or facts that become useful information when organized in a meaningful way; can be qualitative or quantitative.

Data Management

Concerned with "looking after" and processing data, including field data sheets, checking and correcting raw data, preparing data for analysis, and documenting/archiving.

Census

Systematically acquiring and recording information about all members of a given population.

Sample Survey

Selection of a subset within a population to yield knowledge about the population of concern.

Experiment

Performed when there are some controlled variables, and the intention is to study their effect on observed variables.

Observation

Appropriate when there are no controlled variables and replication is impossible, typically using a survey population.

Sampling Frame

A subset of items possible to measure from the population.

Nonprobability Sampling

Any sampling method where some elements of the population have no chance of selection or where the probability of selection can’t be accurately determined.

Convenience Sampling

Selecting subjects based on the availability of the subject.

Quota Sampling

When judgment is used to select the subjects based on specified proportions.

Probability Sampling

It is possible to both determine which sampling units belong to which sample and the probability that each sample will be selected.

Simple Random Sampling (SRS)

All samples of a given size have an equal probability of being selected, and selections are independent.

Systematic Sampling

Relies on dividing the target population into strata (subpopulations) of equal size and then selecting randomly one element from the first stratum and corresponding elements from all other strata.

Stratified Sampling

When the population embraces a number of distinct categories, the frame can be organized by these categories into separate “strata”. Each stratum is then sampled as an independent sub-population.

Cluster Sampling

Sometimes it is cheaper to ‘cluster’ the sample in some way (e.g. by selecting respondents from certain areas only, or certain time-periods only).

Matched random sampling

In this method, there are two (2) samples in which the members are clearly paired, or are matched explicitly by the researcher.

Blocking

Using blocking to reduce the influence of confounding variables and randomized assignment of treatments to subjects.

Experimental unit

An experimental unit is subjected to treatment.

Control Group

A control group is not subjected to treatment.

Random Assignments

Randomization of allocation of (controlled variables) treatments to units.

Replication

To reduce variability, in the experiment the measurements must be repeated.

Confounding variable

An extraneous variable in a statistical model that correlates (positively or negatively) with both the dependent variable and the independent variable.

Placebo

An imitation pill identical to the actual treatment pill, but without the treatment ingredients.

Placebo effect

A sham (or simulated) effect when medical intervention has no direct health impact but results in actual improvement of a medical condition because the patients knew they were treated.

Blinding

Is a technique used to make the subjects “blind” to which treatment is being given.

Blocking

Is the arranging of experimental units in groups that are similar to one another.

Blocking factor

A source of variability that is not of primary interest to the experimenter.

Completely randomized designs

Are for studying the effects of one primary factor without the need to take other nuisance variables into account.

Randomized block design

Is a collection of completely randomized experiments, each run within one of the blocks of the total experiment.

Matched pairs of design

Is its special case when the blocks consist of just two (2) elements (measurements on the same patient before and after the treatment or measurements on two (2) different but in some way similar patients).

Chi-square test

Is used to determine whether there is significant difference between the expected value frequencies and the observed frequencies in one or more categories

Chi-square goodness of fit test

Determines if a sample data matches a population.

Chi-square test for independence

Compares two (2) variables in a contingency table to see if they are related.