# PSYC 210 Lecture Notes - Kelvin, Normal Distribution, Unimodality

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Published on 14 Sep 2012

Department

Psychology

Course

PSYC 210

Professor

September 4th, 2012 1

Branches of Statistical Methods:

Descriptive – summarizes or describes the data

Inferential – infers a conclusion based on the data

Types of Variables:

Equal-interval – the difference between two successive categories are the same (assume equal-interval up to

Chapter 12)

Temperature measured with Fahrenheit has equal intervals; the difference between temperatures of 30

and 31 degrees is 1 degree, and the difference between 100 and 101 degrees is 1 degree. No matter

where on the scale that 1 degree is located, that 1 degree represents the same amount of heat.

When using a ruler to measure the length of something, the difference between 2 and 3 inches is 1 inch,

and the difference between 10 and 11 inches is 1 inch -- no matter where on the ruler that 1 inch lies, it

still represents the same amount of distance

Ratio – just like interval, except that a variable on the ratio scale has a true zero point--a beginning or ending point

“I’m twice as tall as you!”

Kelvin temperature scale, height, length, etc

Rank-order – no equal “difference” between ranks

i.e., the order in which athletes come in rank: 1st, 2nd, 3rd

Nominal – no numerical value; the order or sequence of nominal variables is not prescribed

qualitative classification

example: gender

Discrete variable – Variable that is measured solely in whole units, e.g., gender and siblings; “Can’t have 4.5 dogs”

Continuous variable – A variable that may have fractional values, e.g., height, weight and time; “You can have

85.5%, 85%, even 85.333333333333%”; infinite values

Types of Graphs and Shapes:

Frequency polygon (“line graph”)

Histogram (“bars that touch”, continuous, numerical)

Bar Graph (nominal, discrete)

## Document Summary

Inferential infers a conclusion based on the data. Equal-interval the difference between two successive categories are the same (assume equal-interval up to. Temperature measured with fahrenheit has equal intervals; the difference between temperatures of 30 and 31 degrees is 1 degree, and the difference between 100 and 101 degrees is 1 degree. No matter where on the scale that 1 degree is located, that 1 degree represents the same amount of heat. Ratio just like interval, except that a variable on the ratio scale has a true zero point--a beginning or ending point. Rank-order no equal difference between ranks i. e. , the order in which athletes come in rank: 1st, 2nd, 3rd. Nominal no numerical value; the order or sequence of nominal variables is not prescribed qualitative classification example: gender. Discrete variable variable that is measured solely in whole units, e. g. , gender and siblings; can"t have 4. 5 dogs .