Flashcards in Chapter 2 Methods Deck (61)

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31

## When a graph is negatively skewed, the mean, median, and mode are shifted...

### Right.

32

## Range

### The value of the largest measurement in a frequency distribution minus the value of the smallest frequency.

33

## Standard Deviation

### A statistic that describes the average difference between the measurements in a frequency distribution and the mean of that distribution.

34

## Scientific research aims to establish...

### Causal relationships between properties.

35

## Variable

### A property whose value can vary across individuals or over time.

36

## Correlation

### Two variables are said to be correlated when variations in the value of one variable are synchronized with variation in the value of the other.

37

## Positive Correlation

### More-more or less-less.

38

## Negative Correlation

### More-less or less-more.

39

## Correlation Coefficient

### Measure of the direction and strength of a correlation.

40

## Natural Correlation

### A correlation observed in the world around us.

41

## Third-Variable Correlation

### The fact that two variables are correlated only because each is causally related to a third variable.

42

## Matched Samples

### A technique whereby the participants in two groups are identical in terms of a third variable.

43

## Matched Pairs

### A technique whereby each participant is identical to one other participant in terms of a third variable.

44

## Third Variable Problem

### The fact that a causal relationship between two variables cannot be infererred from the naturally occuring correlation between them because of the ever-present possibility of third-variable correlation.

45

## Experiment

### A technique for establishing the causal relationship between variables.

46

## Experiments can eliminate differences by ___ and ___.

### Manipulation and random assignment.

47

## Manipulation

### Creation of an artificial pattern of variation in a variable on irder to determine its causal powers.

48

## Independent Variable

### The variable that is manipulated in an experiment.

49

## Experimental Group

### The group of people who are treated in a particular way, as compated to the control group, in an experiment.

50

## Control Group

### The group of people who are not treated in the particular way that the experimental group is treated in an experiment.

51

## Dependent Variable

### The variable that is measured in a study.

52

## Self-Selection

### A problem that occus when anything about a person determines whether he or she will be included in the experimental or control group.

53

## Random Assignment

### A procedure that uses a random event to assign people to the experimental or control group.

54

## Internal Validity

### The characteristic of an experiment that establishes the causal relationship between variables.

55

## External Validity

### A property of an experiment in which the variables have been operationally defined in a normal, typical, or realistic way.

56

## Population

### The complete collection of participants who might possibly be measured.

57

## Sample

### The partial collection of people drawn from a population.

58

## Case Method.

### A method of gathering scientific knowledge by studying a single individual.

59

## Random Sampling

### A technique for chooseing participants that ensures that every member of a population has an equal chance of being included in the sample.

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