Transcript ppt

Intro to SPSS
Kin 260
Jackie Kiwata
Overview

Intro to SPSS





Defining Variables
Entering Data
Analyzing Data
SPSS Output
Analyzing Data




Max, Min, Range
Percentiles
Mode, Median, Mean
Standard Deviation
What is SPSS?



Stands for Statistical Package for the
Social Sciences
Well suited for survey and experimental
research
Includes statistical analysis and
graphical presentation of data
Opening SPSS


Start > Programs
> Coursework >
SPSS
Choose Type in
data to begin
The SPSS Windows


Data View: Used for data input
Variable View: Used for adding variables
and defining variable properties
How to use SPSS in general
1.
2.
3.
4.
Define variables in Variable View
Enter data in Data View
Analyze
Get Output
Step 1 – Enter variables in
Variable View
Variable Name

Assign a brief & meaningful name to variables
 No white space allowed in variable names
 Default is var00001
e.g. “VO2max”, “Grade”
Variable Type

Value Labels

Text data should be assigned to String type
 Numeric data assigned to Numeric type
e.g. The variable “Name” assigned to String
e.g. The variable “GPA” assigned to Numeric
Use value labels for variables with constant
values
e.g. The variable “Gender” would have Male and
Female labels
Ex 1 – Defining Variables

Define 2 variables


Name – name of person
GPA – grade point average with 2 decimal
places
Step 2 - Enter Data



Enter data after defining variables
If variables are defined as Numeric,
SPSS will only accept numeric digits
If variables are defined as String, SPSS
will accept any keyboard character
SPSS Data Editor



Variables = Columns
Cases = Rows
Cell = Intersection of Variable & Case
Ex 2 – Enter Data
Name
GPA
Jimmy
3.52
Sheila
2.57
Amanda
3.89
Derek
3.60
Step 3 – Analyze Data

Today, we will analyze:





Minimum, maximum, range
Percentiles
Mode, median, mean
Standard Deviation
Should know concept and/or how to do
by hand in addition to using SPSS
Step 4 – Output
Ex 3 – Find Mean of GPA

Use SPSS to find the GPA mean of the
students
Ex 4 – Find Min, Max, Range by
Hand
Basketball Free Throws Completed in 10 attempts




H: highest score (max)
L: lowest score (min)
R: range from highest to
lowest score.
R=H-L
N: number of scores
X
10
9
9
7
7
7
6
5
5
5
4
4
3
3
1
Ex 5 - Find min, max, range
using SPSS
Go to:
Analyze >
Descriptive Statistics >
Frequencies
1.
SPSS: Frequencies
2. Add variables to analysis
3. Click on Statistics button
SPSS: Statistics
4. Checkbox the statistics
SPSS: Output
Frequencies
Saving Output Table
Tables/graphs generated in SPSS can be copied from
SPSS Output and pasted into a Word document
1.
In the SPSS Output window, right click the table.
A box appears around the table and a red arrow
to the left of it.
2.
Select Copy objects from the menu
3.
Paste into Word.
NOTE: The object is copied as a picture into Word.
The data within the picture cannot be edited.
Percentiles



A point on a continuous scale of 100
divisions such that a certain fraction of
raw scores lies at or below that point
e.g. The 75th percentile is equal to or
better than ¾ of the scores
e.g. The 50th percentile is equal to or
better than ½ of the scores
Percentile Problem


A high school basketball coach decides
the 60th percentile should be the cutoff
point for selecting varsity team athletes.
If the coach uses free throw scores as a
criterion, how many baskets must a
player make to qualify?
By Hand - Percentiles
1.
2.
3.
Convert percentile to decimal
Multiply decimal by N and round off to
the nearest integer.
Value obtained is the number of
scores from the bottom, so count from
the bottom up.
By Hand – Percentiles, con’t.
X = Basketball free
throws completed in
10 attempts
1. Convert percentile to decimal.
60% = .60
2. Multiply decimal by N and round off if
necessary
.60 * 15 = 9
3. Count that many scores from the
bottom up.
9 scores from the bottom is 6.
Therefore, a player needs to make
6 or more free throws in order
to qualify.
10
9
9
7
7
7
6
5
5
5
4
4
3
3
1
N=15
H=10
L=1
R=10-1=9
SPSS - Percentiles
1. Analyze >
Descriptive
Statistics >
Frequencies >
Statistics
2. Enter
percentile
Percentile Output

What’s wrong with this result?
Mode

The score that occurs most frequently



Can be bimodal or multimodal
E.g. 1, 2, 3, 4, 4, 5, 5, 5, 6, 6, 6, 7
Mode = ?
Median

The score associated with the 50th %


It is the middle score; divides data set in half
If N is even, take midpoint and round up to
nearest integer
9
8
6*
4
1
19
18
median
17* reported
median
16
13
12
Mean


The average
Sum the scores and divide by N
e.g. 1, 2, 3, 4, 5
Mean = (1+2+3+4+5)/5 = 3
Ex 6 – Find Mode, Median,
Mean through SPSS
X = Basketball free throws completed in 10 attempts
10
9
9
7
7
7
6
5
5
5
4
4
3
3
1
SPSS – Mode, Median, Mean
1. Analyze >
Descriptive
Statistics >
Frequencies >
Statistics
2. Check Mean,
Median, Mode
Ex 6 Output
Standard Deviation

A statistic that tells you about the spread, or
variability of the data set


How tightly is the raw data clustered around the mean?
How far are the scores from the average?
Use the normal curve to
illustrate the concept of standard
deviation

Standard Deviation con’t.

Large SD indicates many data points are far
from the mean


Normal curve is longer and flatter
Small SD indicates many data points are
close to the mean

Normal curve is steeper and narrower
SPSS – Standard Deviation
References


SPSS Guide:
http://www.calstatela.edu/its/docs/pdf/SPSS1
4Part1.pdf
Standard deviation


In depth:
http://en.wikipedia.org/wiki/Standard_deviation
Simple:
http://www.robertniles.com/stats/stdev.shtml