PSYCHOLOGICAL STATISTICS REVIEWER (PSYCHNOTES)

Statistics

it is a science of data, and in statistics it involves summarizing, analyzing, and interpreting the information or numerical info.

is a way of viewing reality as exists around us in a way that we otherwise could not.

Population

set of all individuals or group of people of interest in a particular study

Parameter

\- a numerical value that describe a population,

Sample

set of individuals selected from the population that intended to represent the population.

Statistic

\- a numerical value that describe a sample

Variable

it is a characteristic that changes or has different values for individuals.

GENERALIZED

Remember (THE RESULTS FROM THE SAMPLE ARE ________ TO THE POPULATION)

Constant

does not vary, it is the same for every individuals.

Values

possible number or category that a score can have.

Score

particular sample’s value on variable.

Data

(plural) - are measurements or observations

Datum

(singular) - single measurement or observation or this what we called score or raw score.

Data set

collection of measurement or observation

Descriptive Statistics

statistical procedures used to summarize, organize, and simplify data.

It gives glance look to the whole data set gathered from the respondents

Frequency Distribution

it is an organized tabulation of the number of individual located in each category on the scales measurement.

Frequency Table

an ordered listing of number of individuals having each of the different values for particular variable

samples

n= for treating ______

Population

N= _______ data

Median

middle score for a set of data arranged in order of magnitude.

Mean (Average)

most often used in continuous data and discrete data. (Denoted by μ)

Mode

\- is a value which occurs most often or most frequently occurring observation. (𝐷𝑒𝑛𝑜𝑡𝑒𝑑 𝑏𝑦 𝑀𝑜)

Unimodal

one mode or one peak in the distribution

Bimodal

Bimodal

Multimodal

\- three or more peaks in the distribution

Cochran’s Formula

it is use when the population is known (The value should be rounded into hundreds)

Slovin’s Formula

to calculate the sample size necessary to achieve a certain confidence interval when sampling a population.

Proportion

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

Percentage

it expressed as a number out of 100

Multiply the value of proportion to 100

Range

a set of data that is the difference between the highest and the lowest values in the set.

R= = 𝐻𝑖𝑔ℎ𝑒𝑠𝑡 𝑠𝑐𝑜𝑟𝑒 − 𝐿𝑜𝑤𝑒𝑠𝑡 𝑆𝑐𝑜𝑟E

Class Size

\- it gives the size of the table

𝑘 = 1 + 3.32𝑙𝑜𝑔(𝑛)

Class Interval

it determine the width of any class in particular distribution

class mark

\- this is the value between lower limit and upper limit

Standard Deviation

\- is a measure of how dispersed the data is in relation to the mean.

Histogram

Bar like graph of a frequency distribution in which the values are plotted along x-axis and the high of each bar is the frequency of the value(No space ang bars)

Frequency Polygon

continuous line that represents the frequencies of scores within a class interval (it is always based on Histogram)

Column Chart

A data visualization where each category is represented by a rectangle (May space ang mga bars)

Bar Graph

Identical to column charts, but in this chart CATEGORIES are organized vertically on y axis and values are shown in x axis.

Line Graph

(Line plot or line chart)- it is a graph uses a lines to connect individual data points that display quantitative values over a specified time interval. (If our variable is about time this graph is appropriate)

Scatter Plot

uses dots to represent values for two different numeric variables.

Stem and Leaf

is a device for presenting quantitative data in a graphical format, similar to a histogram, to assist in visualizing the shape of a distribution.

Gaussian Curve

is a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean. In graphical form, the normal distribution appears as a "bell curve”

Karl Friedrich Gauss

He coined the term Gaussian Curve

Abraham de Moivre

Who introduce the first concept of Normal Curve

Skewness

is the degree of asymmetry observed in a probability distribution.

Z-Score

a statistical measurement that describes a value's relationship to the mean of a group of values. ____ is measured in terms of standard deviations from the mean. If a ______ is 0, it indicates that the data point's score is identical to the mean score.

Z-Table

tools used to get exact proportion or probability

𝑧 = 𝑥 −MEAN / SD

Formula for z

𝑆𝐷 = x - mean / z

formula For SD

z x Sd + μ

formula for x

x + sd x z

formula for mean

Kurtosis

a measure of the tailedness of a distribution

Mesokurtic

Medium tail

Platykurtic

Flat tail

Leptokurtic

Thin tail

Inferential Statistics

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

T- Test

a statistical test that is used to compare the means of two groups. It is often used in hypothesis testing to determine whether a process or treatment actually has an effect on the population of interest, or whether two groups are different from one another.

Z-test

a statistical test to determine whether two population means are different when the variances are known and the sample size is large. A z-test is a hypothesis test in which the z-statistic follows a normal distribution. A z-statistic, or z-score, is a number representing the result from the z-test.

Difference

A z-test is used to test a Null Hypothesis if the population variance is known, or if the sample size is larger than 30, for an unknown population variance. A t-test is used when the sample size is less than 30 and the population variance is unknown

Similarity

z-tests, t-tests are calculations used to test a hypothesis, but they are most useful when we need to determine if there is a statistically significant difference between two independent sample groups.

Pearson correlation coefficient

assesses the linear relationship between variables,

Spearman correlation coefficient

evaluates the monotonic relationship

Sampling error

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

Discrete variable

A discrete variable consists of separate, indivisible categories. No values can exist between two neighboring categories.(Categorical like male/ female, names and more)

Continuous variable

For a continuous variable, there are an infinite number of possible values that fall between any two observed values. A continuous variable is divisible into an infinite number of fractional parts. (Decimals )

Nominal, Ordinal, Interval, Ratio

Levels of Measurements

Descriptive Statistics

\- One group with one or more separate variables measured for each individual  Numerical or category  Describing the individual variable

Behavioral Observation

observes and systematically records the behaviour of individual to describe the behaviour.

Frequency

kung ilan

Duration

kung gaano kahaba

Interval

period of time between the events

Naturalistic or non-participant, Participant observation, Contrived or structured

Types of observation

Naturalistic

or non-participant- Observe in a natural setting as unobtrusively as possible

Participant observation

engages in the same activity.

Contrived

or structured - arranged specifically to facilitate the occurrence of specific behaviors.

Open-ended, Restricted, Rating scale

Types of Questions

Open-ended

– Anything you want to answer

Restricted

Multiple choices, or something have a restricted question, have a limitations.

Rating scale

Likert- scale

Case study

case study may involve an intervention or treatment administered by the researcher

CASE HISTORY

Not include any treatment

Correlational Research

One group with two variables measured for each individual (determining whether there is a relationship between the two variables)

Limitation

 Demonstrate the existence of relationship  No explanation

 It does not establish the cause and effect

Predictive research design

Predicting the outcome.

Comparative research design-

comparing two or more groups with one variable.

Experimental Research Design

to answer the cause and effect questions about the relationship between two variables.

Manipulation

something purposefully change by the researcher in the environment

Control

used to prevent outside factors from influencing the study outcome

random selection

equal chance and assignment. Equal chance of being assign in treatment

Control condition or group

does not receive ant treatment instead they received neutral or placebo

Purpose= to provide baseline for comparison group

Experimental condition

or group- do receive the experimental treatment

Quasi-experimental Research

uses some of the rigor and control that exist in experiments;

 always contain a flaw prevents from obtaining an absolute cause and effect answer

Pre- test / post-test design

= you will giving before and after treatment and then you will observe if there is any changes of the given treatment or condition

Longitudinal Design

= involved repeted observation of the same variables over short or long period of time. (For years)

Target Population

researcher’s specific interest with the individual share one characteristics.

Accessible Population

can be accessed by the researchers

Representativeness

the characteristics of the sample accurately reflect the char. of the population.

Representative sample

= same characteristics as the population.

Biased sample

different characteristics from population

Selection bias or sampling bias

= are selected in a manner that increases the probability of obtaining a biased sample

Probability sampling

= the entire population is known ( alam mo na dito yung participants mo)

Simple random sampling

= equal chance of being selected. (RANDOM NUMBER GENERATOR)

A second requirement that is sometimes added is that each selection is independent of the others.