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Ap Stats Vocab - specifically For Experimental design

### Bias

a college has 80% full time students and 20% part time. I do a survey of 500 students and on purpose survey 50% full time students and 50% part time. , influence in an unfair way

### Blind Experiment

an experiment in which the subjects do not know whether they are members of the experimental group or the control group.

### Blocking

using extraneous factors to create experimental groups that are similar with respect to those factors, thereby filtering out their effect

### Control

A sample that is treated like other experimental groups except that the independent variable is not applied to it

### Double Blind

a test procedure in which the identity of those receiving the intervention is concealed from both the administrators and the subjects until after the test is completed

### Experimental Design

A design in which researchers manipulate an independent variable and measure a dependent variable to determine a cause-and-effect relationship

### Factor

A commercial asks you to buy something frequently mention a toll-free number. "toll free number" and "price" are examples of this term.

### Hidden Bias

The question may be worded in such a way as to elicit specific response. The ordered of questions might lead to biased responses. Also, the number or response on a Likert scale may force responses that do not reflected the respondent's feelings or experience.

### Level

In one of the previous examples about commercials, commercials were shown where the toll free number was mentioned 1,3, or 4 times, and the price mentioned 2 and 3 times. There numbers each form a different ____.

### Matched Pairs

an observational technique that involves matching each participant in the experimental group with a specific participant in the control group in order to eliminate the possibility that a third variable (and not the independent variable) caused changes in the dependent variable

### nonresponse

occurs when an individual chosen for the sample can't be contacted or does not cooperate

### observational study

a study in which the researcher carefully and systematically observes and records behavior without interfering with the behavior; it may involve either naturalistic or laboratory observation

### randomization

random assignment of experimental units to treatments or of treatments to trials, the best defense against bias.

### sampling frame

the individuals or clusters of individuals who might actually be selected for inclusion in the sample

### simple random sample

this of sample size n is one in which each set of n elements in the population has an equal chance of selection

### statistical inference

Making inferences about the characteristics of the population from the information that is provided by the sample.

### statistically significant

a term used to describe research results when the outcome of a statistical test indicates that the probability of those results occurring by chance is small

### stratified random sample

a sample in which the population is first divided into similar, nonoverlapping groups. A simple random sample is then selected from each of the groups

### table of random digits

A long string of digits 0-9, each with these properties, each entry is equally likely to be any of the 10 digits. Entries are independent

### treatment

I give a set of students a pre-test on their knowledge on the civil war. Then i give them a chapter to read on the subject. Then I give them a post test. The chapter they read would be an example of ____.

### undercoverage

a sampling scheme that biases the sample in a way that gives a part of the population less representation than it has in the population

### voluntary response sample

A sample that consists of people who choose themselves by responding. They often over represent people with strong opinions.

### Cluster sample

a sampling design in which entire groups, aka Clusters, are chosen at random. usually selected at a matter of convenience, practicality or cost. each cluster should be diverse in character and representitive of the population, so all the clusters should be similar to each other

### response bias

preconceived notions of a person answering [a survey] which may alter the experiments purpose, anything in the survey design that influences the responses from the sample.

### convenience sample

when researchers draw participants from the populations that are readily available to them

### voluntary response sample

A sample that consists of people who choose themselves by responding. They often over represent people with strong opinions.

### representative sample

the population is divided into strata and a random sample is taken from each stratum, sample carefully chosen so that the characteristics of the participants correspond closely to the characteristics of the larger population

### placebo

something presented as a drug (or whatever you are trying to test in your experiment), but having no actual effect on the person.

### linearity

the notion that one event is a cause and the other is its effect; in behavior, the idea that one behavior is a stimulus and the other a response. Linear thinking is opposite of circular thinking, in which events are thought to be related in a series of interacting loops

### least squares regression line

The least-squares regression line of y on x is the line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible.

### explanatory variable

the independent variable that attempts to explain the relationship with the other variable. It becomes the x variable on the graph

### response variable

values of this variable record the results of each trial with respect to what we were interested in

### scatterplot

a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation). (Also called a scattergram or scatter diagram.) (Myers Psychology 8e p. 031)

### residual

the difference between a Y value estimated from the regression equation and the actual Y value for each unit - the lower the values of r, the larger the residuals will be