#### The definitions you need to understand what a statistics professor means

**control condition**

*The Book*: Individuals in a **control condition** do not receive the experimental treatment. Instead, they either receive no treatment or they receive a neutral, placebo treatment. The purpose of a control condition is to provide a baseline for comparison with the experimental condition.

*Our Take*: People who are not experimented on directly—the control group.

**correlation method**

*The Book*: Two variables are observed to determine whether there is a relationship between them.

*Our Take*: seeing if there is a connection between two variables

**data**

*The Book*: (plural) are the measurements or observations. A **data set** is a collection of measurements or observations. A **datum** (singular) is a single measurement or observation and is commonly called a **score** or **raw score**.

*Our Take*: the information you get from the study

**dependent variable**

*The Book*: the variable that is observed in order to assess the effect of the treatment.

*Our Take*: the variable that remains the same (i.e., male or female; red or green).

**descriptive statistics**

*The Book*: Statistical procedures used to summarize, organize, and simplify data.

*Our Take*: see statistics below

**experimental condition**

*The Book*: Individuals in the **experimental condition** do receive the experimental treatment.

*Our Take*: the experimental "rats"

**frequency distribution**

*The Book*: An organized tabulation of the number of individuals located in each category on the scale of measurement.

*Our Take*: Listing of data and how often each occurs

**independent variable**

*The Book*: The variable that is manipulated by the researcher. In behavioral research, the independent variable usually consists of the two (or more) treatment conditions to which subjects are exposed. The independent variable consists of the *antecedent* conditions that were manipulated *prior* to observing the dependent variable.

*Our Take*: the variable that changes during the experiment (i.e., take a pill or not take a pill; number of times the red color is chosen versus the number of times the green color is chosen).

**inferential statistics**

*The Book*: Consist of techniques that allow us to study samples and then make generalizations about the populations from which they were selected

*Our Take*: generalizations from statistics

**Negative Skew**

*The Book*:

*Our Take*:

**parameter**

*The Book*: A value, usually a numerical value, that describes a population. A parameter may be obtained from a single measurement, or it may be derived from a set of measurements from the population.

*Our Take*: a population descriptor (i.e., the population average) [see **statistic**]

**population**

*The Book*: The set of all the individuals of interest in a particular study.

*Our Take*: The entire group of people you are trying to get information about.

**Positive Skew**

*The Book*: A skewed distribution with the tail on the right-hand side (above-zero end) of the X-axis.

*Our Take*: Small end on the right

**sample**

*The Book*: A set of individuals selected from a population, usually intended to represent the population in a research study.

*Our Take*: The small group you actually study as opposed to the large group you are trying to get information about.

**sampling error**

*The Book*: The discrepancy, or amount of error, that exists between a sample statistic and the corresponding population parameter.

*Our Take*: the difference between the sample you tested and the actual population

**Skewed Distribution**

*The Book*: Description of the shape of a distribution when the scores tend to pile up toward one end of the scale and taper off gradually at the other end.

*Our Take*: A distribution that extends more to one side than another.

**statistic**

Note: Do not confuse with statisticS

*The Book*: A value, usually a numerical value, that describes a sample. A statistic may be obtained from a single measurement, or it may be derived from a set of measurements from the sample.

*Our Take*: a sample descriptor (average score for a sample, which will probably be different from the average score for the population). [see **parameter**]

**statistics**

*The Book*: A set of mathematical procedures for organizing, summarizing, and interpreting information.

*Our Take*: Statistics is a way to help you interpret data.

**Symmetrical Distribution**

*The Book*: The shape of a graph occurring when it is possible to draw a vertical line through the middle and one side is a mirror image of the other.

*Our Take*: Seeing the same thing on each side of a graph when divided down the middle.

**Tail (of a distribution)**

*The Book*: The section where the scores taper off toward one end of a distribution.

*Our Take*: The small tapered ends of a distribution.

**variable** (see independent and dependent variable also)

*The Book*: A characteristic or condition that changes or has different values for different individuals

*Our Take*: something that changes (see **dependent or independent variable**)