Statistics School Counseling
Terms
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 Independent Variables
 Treatment
 Dependent

Whats measured
The outcome
Depends on treatment(independent)
 Hypothesis
 educated guess
 null hypothesis
 a hypothesis of no difference
 Sampling methods

random
stratified
systematic
cluster
purposive
convenience
snowball
multistage
 Random sampling
 best to use
 stratified sampling
 arranged in some way (alphabetical or by number)
 cluster sampling

Take by cluster
ex. classroom, or every 5th case ect.
 purposive sampling
 they have a purpose for the study
 convenience sampling
 convenient to use them
 snowball sampling
 get one and then they tell someone else who tells someone else and so on
 multistage sampling

large areas targeted then smaller areas randomly
 then in that large sample, they randomly seclect a smaller area
 Sample size
 larger the sample size, less sample error
 face validity

on the surface, does it appear to measure what it is supposed to measure to those taking the instrument
Ex: students leaving the exam were asked if they felt the exam covered what they expected it to cover
 Factual

does it elicit truthful responses
ex: I developed an inventory that measures how ofeten sutdents met with faculty to prepare for the Comprehensive Exam. I piloted it on my own class and found that students reported meeting with me three times more often that my records indicated
 Experimental Approaches

Cause and Effect
 true experiment
group experiment
time series
 quasiexperimental or pre experimental
 Research Designs: Time series

Time series Individual
A B
A B A B
Multiple baseline
individual behavior over time
 Posttest only

Experimental group Treat PT
control group Control PT
weakness, no pretest so you do not know where they began
 One group pretest posttest

Experimental group PT TR PT
no control group, nothing to compare it too
 Factorial/independent groups comparison

Factor 1
x y
a
Factor 2
b
This factor compared to that factor

Mixed design
Pretest Posttest Control group

EXP Group PreT Tr PT
Control Group PreT control PT
 Soloman four group

Perfect design
PreT exp Pret TR PT
Pret control PreT Cont. PT
Untest exp TR PT
untest cont Cont PT
 Wait control

Immediate PreT T Post1 W Post2
Wait PreT W Post1 T Post2
pretest everybody
 Risks to internal validity

Mortality
history
maturation
practice effects
experimentor bias
demand social accept.
rater/observer
istrumentation
regression to mean
 Risks: History

history of peoples roles
ex: In a nursing home and people are answering depression survey after nurse died. Obviously going to feel depressed because nurse took after them.
 Risks: maturation

change over time
ex: drives 1625 do drivers ed program for 16 years old and test at 25, is it because of program or maturation?
 Placebo

experimental only (fake)
 Hawthorne
 are they changing because they know they are being studied
 John Henry
 control group works harderknows they are being studied
 experimenter bias
 start doing what they think the experimenter wants
 deman/social acceptability
 respond most acceptable way
 instrumentation
 create own instrument to test
 regression toward the mean
 if you give a test and get big spread in scores, next time you give test mean will be almost identical but will be closer to the mean causing less variance
 Risk to external validity

can we generalize the results to the population?
population sample differences
artificiality of research
 take participants out of normal environment and put in room with a 2 way mirror
 Range
 highlow = range
 variance
 mean of the squared deviations from the mean of the distribution
 standard deviation
 the square root of the mean of the squared deviations from the mean of a distribution reflects the typical deviation from the mean
 Nominal
 identity
 ordinal
 have rank
 interval
 no zero point
 ratio
 has absolute zero
 Frequency
 how many scores fall in that interval
 percent
 take frequency/ # of scores x 100= %
 histograms

bar charts
 graphs the frequency
compares something
 line graphs

graphs cum. frequency
 Pie Chart

graphs percentages
parts of a whole
 Measures of central tendencies

mean
median
mode
 Measures of variability
 range
 deviations
 distance from mean for each score
 Linear regression
 predicting one variable over another
 factor analysis
 groups questions together to measure something
 Parametric

Assumes normal curve:
Ttest
anova (f test)
 F test
 compares 3 or more means
 Nonparametric

does not assume normal curve
chi square
 Type 1 Error

rejecting the null, accepting the alternative
there is a difference, when in reality no difference
 Type 2 error

Retain the null, reject the alternative
saying there is no difference when really there is
 Lower p value then..
 more likely to commit type 2 error, less likely to commit type 1
 increase sample size...
 will decrease type 2 error
 chi square

nominal data
compares two or more sets of data
assumes random sampling
no cell is less than 5 cases
 Pearson R

straight line relationship
both variables are at least interval
random sampling
normal distribution in sample under 30
1.00 Perfect neg
.60 strong neg
.30 mod neg
.10 weak neg
0 no correlation
.10 weak pos
.30 moderate pos
.60 strong pos
1.00 perfet pos
 Factors that affect reliability

Test length
objectivity of scoring
variability of groups
difficulty of items
 Risks to test validity

History: influence outside events
maturation: normal changes
testing threat: pretesting influences post testing
instrumentation: alternate forms may not be equivalent
statistical regression interaction: combination of the above
 Research Design

General idea: know more about the research
review the literature: go out and review what we already know
measurement: subjects, who is it were studying
subjects: who is it were studying
variables: what are we studying
group assignment: random, non random
analysis plans: analyze data
gathering data: experiment
Treatment & Controls:
Data Analysis: analyze data that was collected
report results
conclusions
 Ethics for Research

Subjects rights:
No harm to subjects
right to privacy
data confidential
purpose
informed consent
purpose for study
what is being done
potential benefit
potential harm
right to withdraw
debriefing/remediation