Exam 2 Flashcards
______ _____ vary along a continuous range; varies in amount rather than kind. Examples
- Weight in pounds
- Age in years
- Pupil dilation in millimeters
_____ _____ can also be categorical. For example, age can be continuous (0, 1, 2…85, 86, 87…) or categorical (infant, child, adolescent, adult).
Time it takes a computer to complete a task. You might think you can count it, but time is often rounded up to convenient intervals, like seconds or milliseconds. Time is actually a continuum: it could take 1.3 seconds or it could take 1.333333333333333… seconds.
A person’s weight. Someone could weigh 180 pounds, they could weigh 180.10 pounds or they could weigh 180.1110 pounds. The number of possibilities for weight are limitless.
Income. You might think that income is countable (because it’s in dollars) but who is to say someone can’t have an income of a billion dollars a year? Two billion? Fifty nine trillion? And so on…
Age. So, you’re 25 years-old. Are you sure? How about 25 years, 19 days and a millisecond or two? Like time, age can take on an infinite number of possibilities and so it’s a continuous variable.
The price of gas. Sure, it might be $4 a gallon. But one time in recent history it was 99 cents. And give inflation a few years it will be $99. not to mention the gas stations always like to use fractions (i.e. gas is rarely $4.47 a gallon, you’ll see in the small print it’s actually $4.47 9/10ths
Continuous variables
______ ______ have relatively distinct categories.
Examples
-Political parties (e.g., Democrat, Republican, Green Party, Reform Party, Libertarian, Independent)
-Ethnic groups (e.g., Latinos, Caucasians, African Americans, Asians, Native Americans, Other)
Categorical variables
_____ ______ refer to categorical variables that have two separate distinct categories.
Examples
oGender (i.e., Male, Female), Yes/No, True/False, Virgin/Not virgin
Dichotomous variables
______ ____ refers to a variable with just two categories that reflects only part of the information available in a more comprehensive variable.
o“Region” (i.e., Northeast, Southeast, Central, West) could be ‘dummy coded’ into Northeast (0) versus
all other regions (1).
o “Family structure” (i.e., intact families, stepfamilies, single-parent families, other) could be ‘dummy
coded’ into two-parent, intact families (0) versus all other family forms (1).
Dummy variable
______ ______ refers to a variable which is manipulated, measured, or selected by the researcher in order to observe its relation to some other variable (i.e., dependent variable).
• The IV is also called a predictor variable, input variable, treatment variable, causal variable, and/or explanatory variable.
Examples:
The independent variable is the variable whose change isn’t affected by any other variable in the experiment. Either the scientist has to change the independent variable herself or it changes on its own; nothing else in the experiment affects or changes it. Two examples of common independent variables are age and time. There’s nothing you or anything else can do to speed up or slow down time or increase or decrease age. They’re independent of everything else.
Independent variable (IV)
________– The subject is assigned by the researcher to a certain level/group
Examples
o Subjects are randomly assigned into an experimental group or a control group and compared on some
outcome variable.
o Subjects are assigned into a daily yoga class, aerobics class, or weight training class to see which subjects will lose the most body fat in twelve weeks.
Manipulated IV
_______ – The subject naturally falls into a level (e.g., sex, IQ, age)
Examples
oMen and women are compared to each other on spending habits. (Note: Gender is the IV, and men and
women are the two levels)
o Mexicans are compared to Salvadorians and Guatemalans on level of educational attainment. (Note:
Ethnic group is the IV with three levels: Mexican, Salvadorian, Guatemalan)
Selected IV
_____ ____ refers to the variable that is observed and measured in response to an IV. In other
words, the DV is dependent upon or influenced by the IV. The DV is expected to increase, decrease, or vary in some systematic fashion as the levels of the IV change.
• Also called criterion variable or outcome variable
Dependent variable (DV)
_____ _____ (nuance) refers to any variable (1) that is held constant in a research study by observing only one of its level or (2) that the effects of the variable are accounted for in the analyses.
• _____ _____ are used in research to neutralize the effects of nuances which are not of central focus to
the study but which may affect the observed behavior.
Examples
-Examining differences between genders (IV) on hours of exercise (DV) after controlling for age (CV).
-Assessing whether the price of a cotton shirt (IV) predicts the durability of the shirt (DV) after controlling for thread count (CV).
Control variable
________ ______ – Uncontrolled factors that may or may not be having an effect on the dependent variable.
Examples:
The thing that makes random assignment so powerful is that greatly decreases systematic error – error that varies with the independent variable. Extraneous variables that vary with the levels of the independent variable are the most dangerous type in terms of challenging the validity of experimental results. These types of extraneous variables have a special name, confounding variables. For example, instead of randomly assigning students, the instructor may test the new strategy in the gifted classroom and test the control strategy in a regular class. Clearly, ability would most likely vary with the levels of the independent variable. In this case pre-knowledge would become a confounding extraneous variable.
Extraneous variables (confounding)
_______ ______ ______ – A variable that is postulated to be a predictor of one or more DVs, and simultaneously predicted by one or more IVs.
• Sometimes it refers to a hypothetical variable that is often not observed directly in a research study but is
inferred from the relationship between the IV and DV.
• Its importance lies in its ability to explain the relationship between the IV and DV under the conditions of
the study and under conditions somewhat different from those set up in the study.
• In all types of behavioral research, intervening variables represent the foundation of theory.
Intervening or mediating variables
____ _____ – A variable that affects (i.e., moderates) the direction and/or strength of the relationship between IV(s) and DV.
Examples
- Intelligence (independent variable)
- Grades (dependent variable)
- Academic motivation (moderation variable)
Moderating variables
________
-To infer that one variable causes another, three criteria are essential:
Examples:
- Because the alarm was not set, we were late for work.
- The moon has gravitational pull, consequently the oceans have tides.
- Since school was canceled, we went to the mall.
- John made a rude comment, so Elise hit him.
- When the ocean is extremely polluted, coral reefs die.
- The meal we ordered was cheaper than expected, so we ordered dessert.
CAUSE/EFFECT
A tentative statement about the expected relationship between two or more variables. In other words, it is a testable conjectural statement about supposed relationships between variables. Hypotheses are the link between theoretical ideas and empirical data.
Hypotheses should…
- Predict a particular relationship between two or more variables
- Be stated clearly, unambiguously, briefly, and in a declarative sentence v Reflect the theory or literature that they are based upon
- Be testable
Hypothesis
_____ _____ refers to the hypothesis of no difference or relationship; statements of equality. Any differences must be assumed to be due to chance.
• The ____ _____ provides a benchmark in which to compare any observed outcomes to see if these
differences are due to chance or some other factor.
• The _____ ____ cannot be directly tested since it refers to the population. If the obtained value (i.e., test
statistic) is more extreme than the critical value (i.e., table value), the ____ ____ cannot be accepted.
Examples
-There is no significant difference between boys and girls on adolescent reports of self-esteem.
-Consumers’ satisfaction with a new product is not significantly related to future sales of the product.
-There is no relationship between furniture comfort on work productivity after controlling for temperature,
light, and wall color.
Null hypothesis
______ _____ states the anticipated relationship in declarative sentence form.
• Philosophically speaking, it is not possible to prove or accept the alternative hypothesis, but it is possible to reject the null hypothesis.
• The _____ ______ that the researcher is usually more interested in is evaluated indirectly by testing the null hypothesis statistically.
Examples
-Adolescent boys will report significantly higher self-esteem than girls.
-Consumers’ satisfaction with a new product is positively related to amount of future sales of product.
-Furniture comfort is significantly and positively related to work productivity after controlling for
temperature, light, and wall color.
Alternative hypothesis
