PSYCHSTAT MIDTERMS

STATISTICS

a branch of mathematics that deals with the organization, summarization, analysis, and interpretation of groups of numbers.

• It proves hypothesis

POPULATION

the set of all the individuals of interest in a particular study

• scope of interest

• generalized from the sample

PARAMETER

the numerical value that describes a population

STATISTIC

the numerical value that describes a sample

SAMPLE

a set of individuals selected from a population, usually intended to represent the population in a research study

VARIABLE

a characteristic or condition that changes or has different values for different individuals

• area of interest

• it can be 2 or more, depending on the study

VALUES

possible number or category that a score can have

SCORE

also called as raw score, is a particular person’s value on a variable

DATA

are measurements or observations

DATA SET

collection of data

DESCRIPTIVE STATISTICS

statistical procedures used to summarize, organize, and simplify data

INFERENTIAL STATISTICS

consists of techniques that allow us to study samples and then make generalizations about the population from which they were selected

SAMPLING ERROR

the naturally occurring discrepancy, or error, that exists between a sample statistic and the corresponding population parameter

DISCRETE VARIABLE

consists of separate, indivisible categories (Whole numbers)

CONTINUOUS VARIABLE

there are an infinite number of possible values that fall between any two observed values (has decimals)

DICHOTOMOUS VARIABLE

one that takes on one of only two possible values observed or measured (only 2 choices)

LEVELS OF MEASUREMENT

a classification that describes the nature of information within the values assigned to variables

NOMINAL

variable with values that are categorical variables

ORDINAL

numeric variable in which the values are ranks; also known as rank-order variable

consists of a set categories that are organized in an ordered sequence

INTERVAL

variable that contains equal-interval between numbers and contain no absolute zero point

RATIO

an interval scale with the additional feature of an absolute zero point

INTERVAL

most psychological variables are ordinal. However, most psychologists treat those data as _______ because it is more flexible for statistical manipulation or analysis

DATA STRUCTURE 1

data structure that has one group with one or more separate variables measured for each individual

DATA STRUCTURE 2

data structure that has one group with two variable measured for each individual

DATA STRUCTURE 3

data structure that compares two or more groups of scores

DESCRIPTIVE RESEARCH

involves measuring one or more separate variables for each individual with the intent of simply describing the individual variables

Emphasizes what exists, rather than why it exists

SURVEY RESEARCH

obtaining data about people’s opinions, attitudes. preferences, and experiences that are hard to observe directly

may be obtained using questionnaires and interviews

NON-EXPERIMENTAL RESEARCH METHOD

observes and measure and variables as the naturally occur without manipulating them

CORRELATIONAL METHOD

determines whether there is a relationship between the variables

EXPERIMENTAL METHOD

one variable is manipulated, one is being observed / measured

aims to establish cause-and -effect relationship

QUASI-EXPERIMENTAL DESIGN

often seem like a real experiment, but they lack one or more of its essential elements, such as manipulation of antecedents and random assignment to treatment conditions

PRETEST / POSTTEST DESIGN

pretest - intervention - posttest - analysis

NONEQUIVALENT GROUPS DESIGN

compares the effects of different treatment conditions on pre-existing groups of subjects'; random assignment is not possible in this design

EX-POST FACTO STUDY

investigates the potential effects of an independent variable after it has already occurred

• after the fact

LONGITUDINAL DESIGN

a method in which the same group of subject is followed and measured at different points in time; a method that looks for changes across time

INDEPENDENT VARIABLE

• intentionally manipulates

• cause

DEPENDENT VARIABLE

• outcome variable

• affected and is measured

EXPERIMENTAL CONDITION

a condition in an experiment wherein the subjects will receive the experimental treatment

CONTROL CONDITION

a condition in an experiment wherein the subjects do not receive the experimental treatment

FREQUENCY DISTRIBUTION

an organized tabulation of the number of individual located in each category on the scale of measurement

FREQUENCY TABLE

ordered listing of number of individuals / objects / respondents having each of the different values for a particular variable

PROPORTION

it measures the fraction of the total group that is associated with each score

PERCENTAGE

an amount of something, often expressed as a number out of 100

GROUPED FREQUENCY

frequency table in which the number of individuals is given for each interval of values

INTERVAL

range of values in a grouped frequency table that are grouped together

HISTOGRAM

appearance of a city skyline

FREQUENCY POLYGON

continuous line, connected through a point

COLUMN CHART

for categorizing / nominal values

BAR GRAPH

identical to column chart, but it is organized vertically on the y-axis

LINE GRAPH

line plot / line chart

displays quantitative values over a specified time interval

CENTRAL TENDENCY

mean median mode

MEAN

average

WEIGHTED MEAN

average in which each observation in the data set is assigned or multiplied by weight before summing to a single average value

MEDIAN

middle score, used when there is an outlier

MODE

most frequently occurring values

categorical and rarely used in research

UNIMODAL DISTRIBUTION

BIMODAL DISTRIBUTION

MULTIMODAL DISTRIBUTION

RECTANGULAR DISTRIBUTION

SYMMETRICAL DISTRIBUTION

SKEWED DISTRIBUTION

the scores pile up on one side of the middle and are spread out on the other side; distribution that is not symmetrical

POSITIVELY SKEWED

the peak is on the left side, the tail is on the right

floor effect

NEGATIVELY SKEWED

the peak is on the right side, the tail is on the left

ceiling effect

NORMAL DISTRIBUTION

bell-shaped, symmetrical and unimodal

KURTOSIS

the extent to which a frequency distribution deviates from a normal curve in terms of whether its curve in the middle is more peaked or flat than more normal

LEPTOKURTIC

the scores are concentrated toward the mean - medyo patayo

MESOKURTIC

normal curve in kurtosis

PLATYKURTIC

the scores have an extremely large deviation from the mean - pa flat na siya

VARIABILITY

describes the distribution

measures how well an individual score represents the entire distribution

RANGE

distance covered by the scores

VARIANCE

measure of how spread out a set of scores are; average of the squared deviation from the mean

DEVIATION

the difference between a score and the mean

STANDARD DEVIATION

approximately the average amount that scores in a distribution vary from the mean

DEFINITIONAL FORMULA

equation for a statistical procedure directly showing the meaning of the procedure.

COMPUTATIONAL FORMULA

equation mathematically equivalent to the definitional formula. Easier to use for figuring by hand, it does not directly show the meaning of the procedure

BIASED STATISTICS

if the average value of the statistic either underestimates or overestimates the corresponding population parameter

UNBIASED STATISTICS

if the average value of the statistic is equal to the population parameter

Z-SCORE

number of standard deviations that a score is above (or below, if it is negative) the mean of its distribution

It is an ordinary score transformed so that it better describes the score’s location in a distribution

STANDARDIZED DISTRIBUTION

Is composed of scores that have been transformed to create predetermined values for µ and σ

Used to make dissimilar distributions comparable

PROBABILITY

The extent to which an event is likely to occur as determined by the fraction or proportion of successful outcomes to all the possible outcomes

OUTCOME

Term used in discussing probability for the result of an experiment (or almost any event)

RANDOM SAMPLING

Requires that each individual in the population has an equal chance of being selected

A sample obtained by this process is called simple random sample

SAMPLING WITH REPLACEMENT

Keeping the probabilities from changing from one selection to the next returning each individual to the population before you make a selection

ADDITION RULE

“or rule”, is used when there are two or more mutually exclusive outcomes

MULTIPLICATION RULE

“and rule”, is used when figuring probability of getting both of two (or more) independent outcomes

SAMPLING FRAME

Specific list of the members of the population in order to select a subset of that population

ELEMENT

Basic unit that represents whatever is being sampled and from which survey data are to be gathered

PROBABILITY SAMPLING

Uses randomization to make sure that every element of the population gets an equal chance to be part of the selected sample

SIMPLE RANDOM SAMPLING

Participants has an equal chance of getting selected to be the part sample

STRATIFIED RANDOM SAMPLING

Divides the elements of the population into small subgroups (strata) based on the similarity in such a way that the elements within the group are homogeneous and heterogeneous among the other subgroups formed.

CLUSTER SAMPLING

Entire population is divided into clusters or sections and then the clusters are randomly selected. All the elements of the cluster are used for sampling.

SINGLE STAGE

stage of cluster sampling - entire cluster is selected randomly for sampling

TWO STAGE

stage of cluster sampling - first, we randomly select clusters and then from those selected clusters we randomly select elements for sampling

SYSTEMATIC SAMPLING

a probability sampling method were the elements are chosen from a target population by selecting a random starting point and selecting other members after a fixed sampling interval

MULTISTAGE SAMPLING

combination of one or more methods of sampling

NON-PROBABILITY SAMPLING

A sampling technique where the samples are gathered in a process that does not give all the individuals in the population equal chances of being selected

CONVENIENCE SAMPLING

The samples are selected based on the availability

PURPOSIVE SAMPLING

Sampling technique that is based on the intention or the purpose of study

QUOTA SAMPLING

Sampling technique wherein the assembled sample has the same proportions of individuals as the entire population with respect to known characteristics, traits, or focused phenomenon.

REFERRAL / SNOWBALL SAMPLING

This technique is used in the situations where the population is completely unknown and rare.