psychstasts terminology

any specific collection of objects of interest.

population

any subset of a larger set of data – to draw inferences about

the larger set called the population

sample

is a collection of methods for collecting, displaying, analyzing,

and drawing conclusions from data.

statistics

is the branch of statistics that involves organizing,

displaying, and describing data.

descriptive statistics

- is the branch of statistics that involves

drawing conclusions about a population based on information

contained in a sample taken from that population.

inferential statistics

data that can take any value. Height,

weight, temperature and length are all examples of data that

will change over time;

continuous data

data that can only take certain or fixed values.

discrete values

are properties or characteristics of some event, object, or person

that can take on different values or amounts.

Variables

the variable the experimenter changes or

controls and is assumed to have a direct effect on the dependent

variable or the “predictor”

Independent variable

predicted variable or measured variable

Dependent variable

Scales or Level of Measurement of Data

Nominal Scale,Ordinal Scale,Interval Scale,Ratio Scale

is an explicit listing of all the individual measurements, either

as display with space between the individual measurements, or in set

notation with individual measurements separated by commas.

Data list

a table in which each distinct value x is listed in

the first row and its frequency (f)

Data frequency table

-is a method of organizing raw data in a compact form by displaying a

series of scores in ascending or descending order,

Frequency Distribution Table

or typical value for a probability distribution. It

may also be called a center or location of the distribution. (You can think

of it as the tendency of data to cluster around a middle value.)

central tendency

The three measures of central tendency

mean, median and mode.

The Mean (x̅) - arithmetic average

The Median ( x̃ )- positional average.

the middlemost value in the data set. It is found midway between the

highest and the lowest value in a rank order distribution and divides

the distribution into two equal parts

Mode

It is quite possible to have two sets of observations with the

same mean or median, but may not describe the behavior of

whole data. It differs in the amount of spread about the mean. So

measures of variability describe how the values are scattered or

clustered about the typical value which is the mean.

MEASURES OF VARIABILITY

- the simplest measure of variability. It is the difference

between the largest value and the smallest value.

Range (R)

Average Deviation (AD) or Mean Deviation

the dispersion of a set of data about the average.

the average of the square deviation from the mean.

Variance of Grouped Data (S2)

The value that divides a set of data into equal parts. Specifically,

quantiles which divide the data into:

Quantiles

- is a degree of asymmetry observed in a probability distribution

that deviates from the symmetrical normal distribution (bell curve) in a given set

of data.

Skewness

– is the peakedness of the curve. Kurtosis refers to the degree of

presence of outliers in the distribution.

Kurtosis

is a degree of asymmetry observed in a probability distribution

that deviates from the symmetrical normal distribution (bell curve) in a given set

of data.

Skewness

describes the position of a raw score in terms of its

distance from the mean, when measured in standard deviation units.

z-score

The z-score is positive if the value lies above the mean, and negative if it lies

below the mean. It is also known as a

standard score