Download QMS102/204- Tips and Links

QMS102/204- Tips and Links
SPSS Tutorial Links
™ http://pages.infinit.net/rlevesqu/spss.htm
(Includes QuickTime tutorial videos)
™ http://cs.furman.edu/rushing/mellonj/spss1.htm
™ http://www.ilstu.edu/~mshesso/SPSS/tutorial.html
™ https://vapps.ryerson.ca
(Run SPSS online)
Keith wasn't
sure, but he
estimated that
his lack of
understanding
did not deviate
significantly from
what he already
knew.
Cartoon by J.
Pennington
Term Test & Exam Tips
•
Do a crib sheet for every chapter.
o Highlight the points you have difficulties on for each chapter crib sheet
o Use the difficulty points on your final crib sheets for the quizzes and
exams
o Organize the points into sections (i.e. 5.2 is Binomial Probability, 3.1 is
Mean, Median, etc.)
ƒ This will minimize the time spent looking at crib sheets on your
quizzes and exams. Hence, more time will be saved for solving the
questions.
•
Color code your text if necessary and study in a disordered pattern
o Color coding your text, will help you understand which information you
find more difficult.
ƒ This will help you organize your crib sheet and help you study for
your term tests and exams.
o Developing a disordered study pattern (i.e. study backwards, forwards,
come back to random sections), helps you prep for exams, since exam
problems are not always structured in the order of the text.
ƒ This may also incline your aptitude to solve statistical problems,
since you are developing the ability to critically think from all
angles.
•
Write down the standards your professor told you to use
o Studying is only half of the preparation for exams. You must attend
classes and make sure you know how your professor wants solutions
written down on the quizzes and exams.
ƒ If you cannot remember your professors’ format to write solutions,
then integrate them into your crib sheet.
Sample Crib Sheet
There is a sample crib sheet on the following page. Organizing your points into defined
blocks may help you find information efficiently and use your crib sheet more
effectively. Please remember a crib sheet is a “tool” and not a “distorted medium”.
Putting size 5 font and filling the paper, does not help you on exams. Rather, this takes time
away from you solving problems and is instead an obstacle than a tool.
Measures of Central Tendency: A single value to represent the data set.
By: Sulosan Thangarajah
1
Measures of Variability: A single value to describe how spread the data is.
•
•
Measures of Central Tendency
– Mode
– Median
– Mean
– Shape
– 10% Rule
Measures of Variability
– Range
– IQR
– Standard deviation
Coefficient of Variation (CV)
Range, IQR, Variance, Std. Dev: Measure of variability are absolute measures.
If you would like to compare the variability of two or more factors, it would be better to use the relative
measures - CV
To Determine CV Closeness use 10% Rule
s is sample
Difference = CV1 – CV2
s
CV = x100
10% of the smaller (of CV1 or CV2)
x
Decision Rules:
1. If Difference < 10% of smaller ; CV1 is equal to CV2; same variability
2. If Difference > 10% of smaller ; CV1 is NOT equal to CV2; different variability
Calculating Percentiles:
nk
n = the number of elements in our data set i =
100
If i is a whole number, ADD 0.5
If i is a fraction, ROUND UP
1.
2.
3.
4.
Measures of Variability
Range (R)
• R=High - Low
Interquartile Range (IQR)
• IQR = Q3 – Q1
• That is, it is the difference between
the 75th and 25th percentiles of a
variable.
Variance
Standard Deviation: standard deviation is
simply the square root of the variance
∑ (x − x )
n −1
2
s=
σ is population
CV =
σ
x100
μ
Shapes:
(1) Symmetrical
Each half of the curve is a mirror image of the other half
of the curve. The low and high values on the scale
balance,
Mean = Median
(2) Left-skewed (Negative Skewed)
Most of the data are in the upper portion of the
distribution. A long tail and distortion to the left that is
caused by some extremely small values. These extremely
small values pull the mean downward so that,
Mean < Median.
(3) Right-skewed (Positive Skewed)
Most of the data are in the lower portion of the
distribution. A long tail and distortion to the right that is
caused by some extremely large values. These extremely
large values pull the mean downward so that,
Mean > Median.
Describing Frequency Distributions:
1. Where is the middle? (Measures of central tendency)
2. How wide is the distribution? (Measures of Variability/Dispersion) The terms variability, spread, and
dispersion are synonyms, and refer to how spread out a distribution is
3. Is the distribution skewed or symmetric? (Measures of Skewness)
4. Is it pointed or stoop? (Measures of Kurtosis)
Characteristics of R, IQR, Var, & Std Dev.
1. The more spread out, or dispersed, the data are, the larger the R, IQR, Var, Std Dev.
2. The more concentrated, or homogeneous the data are, the smaller the R, IQR, Var, Std Dev.
3. If the values are all the same (so that there is no variation in the data), the R, IQR, Var and Std Dev = 0
4. None of the measure of variation (R, IQR, Std Dev) can ever be negative.
Making Data Informative:
I. Organizing
II. Present
III. Describe
IV. Analyze
By: Sulosan Thangarajah
Stem and Leaf Display
Frequency Distribution
(Relative/Percent)
OGIVE
2
Numerical Descriptive
Measures (Descriptive
Statistics)
Measures of
Central Tendency
Measures of
Variability