PSYCHOLOGY STATISTICS (chapter 1)

Statistics

Science of collection, presentation, analysis, and reasonable interpretation of data

two types of statistics

descriptive and inferential ttatistics

Descriptive Statistics

Aims to describe given set of data but it cannot draw conclusions

Inferential Statistics

Aims to draw conclusion and predictions about the set of data

The focus of descriptive statistics is to ___________

DESCRIBE data

The focus or goal of inferential statistics is to

make decisions about population characteristics

The three fundamental elements of statistics

Experimental, Population, Variable

It is the subject in which researchers collect data (i.e: people)

Experimental

All items of interest

Population

2 Types of variable

Independent and dependent variable

2 Types of variable

Independent and dependent variable

presumed CAUSE

Independent variable

presumed EFFECT

dependent variable

Two types of data

Qualitative and Quantitative data

Qualitative

Non-numeric and can only be classified into categories.

Quantitative

measurements that are recorded on a natural occuring numerical scale; numeric on nature

Four sources of data

Published source, designed experiment, survey, observation data

example of this source is book, journal newspaper, website

Published source

Designed experiment

researchers exerts strict control of unit

a group of people are surveyed and their responses are controlled

survey

Representative sample

exhibits characteristics that represent the population of interest

Every sample has an equal chance of being chosen but not eveyone will be chosen

random sample

Problems with non-random sample

selection bias, nonresponse bias, measurement error

A subset of the experimental units in the population is excluded, these units have no chance of being selected for the sample

Selection bias

Nonresponse bias

the researchers conducting a survey or study are unable to obtain data on all experimental units selected for the sample

innacuracies on the values of the recorded data. In surveys, errors due to ambiguous or leading questions and the interviewers effects on the respondent

Measurement error

Nominal

describes, names, and labels the characteristics of a group

no inherent ranking order it only categorize cases

Nominal

gender, ethnicity, blood type, coffee preference

example of nominal data

labels/names categories and has inherent ranking order

ordinal

In this measurement, non-numeric labels can still convey order, as the absence of numbers does not imply a lack of order

ordinal

income level

low income, mid income, high income

example of ordinal data

measured numerically or numerical in nature

numerical data

has magnitude, equal-interval, and has no absolute value

interval

temperature in fahrenheit and celcius

examples of interval

Distance between points is consistent and can be measured. Has absolute zero

ratio

Distance between points is consistent and can be measured. Has absolute zero

ratio

height, weight, length

example of ratio

Temperature in kelvin

ratio

ruler

interval

score in a motivation scale

interval

Discrete

Countable variables. Has no decimal

Continuous

can be acquired through measuring scale and has decimal places or in-between values

Number of students

Discrete

Ratio

it is a matter kung “wala” o “meron”. Wala ritong negative values

Two classifications of variable

discrete and continuous

Mnemonics for Random Sampling

S-S-S-C

Mnemonics for three problems with non-random sampling

S-N-M

Mnemonics for the 4 sources of data

P-D-S-O