School

Simon Fraser UniversityDepartment

PsychologyCourse Code

PSYC 210Professor

Cathy Mc FarlandStudy Guide

MidtermThis

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In-class notes

Lecture 2: January 16, 2012

Summation Notation

- = X1 + X2 + X3 + … + XN

↑i = 1 lower limit of the summation

Algebraic Rules of Summation

- Summary of the constant

oThe sum of k occurrences of constant c

oK = # of constants; k times the constant

o = c + c + c + … + c

= kc

oThis is just simple multiplication but they're trying to make it look complicated

- Summing cX

oThe sum of the k products, where each product is obtained by multiplying a constant by the score

on the variable =equals= the constant times the sum of the variable

o = cX1 + cX2 + … + cXk

= c (X1 + X2 + … + Xk)

= c

- Distributive laws over addition & subtraction

- the summation operator can be distributed across variables or constants when they are added or

subtracted from one another

BUT

Sum of products not generally equal to product of sums

≠ ( )( )

Displaying Data

- Raw Data or Data Scores – the scores obtained from sampling units before the scores are analyzed

statistically

-Frequency Distribution – a set of possible values of a variable in a dataset, along with the count of how

often each value occurs

- Frequency of occurrence – the number of cases in a sample with scores at a specified value

- Relative frequency (fR) – the proportion of the sample with scores at a specified value, then multiplied by a

hundred

ofR =

N is the total # of people in the sample

- Cumulative Frequency – the number of cases with scores at or below the specified value

ofcr =

- Cumulative Relative Frequency – the proportion of the sample with scores at or below the specified value

ofcr =

SCALES Classify Order Equal

distances

True

zero

Nominal X

Ordinal X X

Interval X X X

Ratio X X X X

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