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Research Methods SLPA 454
Research Methods
61
Speech-Language Pathology
Undergraduate 4
07/09/2013

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Term
A Type l error can be prevented by
Definition
setting the alpha level low enough.
Term
A Type l error is committed by
Definition
rejecting the null hypothesis; finding a difference when there is no difference.
Term
A Type ll error is committed by
Definition
accepting the null hypothesis when it should be rejected; there is a difference.
Term
A Type ll error can be prevented by
Definition
getting a large a size of samples as possible.
Term
A statistically significant difference occurs
Definition
when the calculated value from the statistical test that you have used in analyzing the differences is greater than the critical value obtained for a table of probability values from your statistical test.
Term
The critical value is
Definition
a number determined by the alpha the level you select and the number of degrees of freedom you have in your data
Term
When the calculated value is larger than the critical value you can
Definition
reject the null and accept the alternative hypothesis that the means of the two groups are not similar or equal to zero.
Term
When selecting a two-tailed test, you need to have
Definition
a greater difference between the two sets of data than with a one-tailed test in order to find the significant difference.
Term
The one tailed test will have a lower value for
Definition
critical value for the same alpha level than a two-tailed test of significance.
Term
Before you analyze the data, you need to set the
Definition
alpha level and develop a directional or non directional alternative hypothesis.
Term
If you only have two groups of data (behaviors from two types of people) you can analyze whether there are difference between the groups by using a
Definition
t-test.
Term
An independent t-test is used when the two groups of data are
Definition
unrelated in some way, like men vs. women or Nebraska vs. Iowa.
Term
Differences between two unrelated groups of people are considered
Definition
independent and are analyzed differently than if they were related samples of data.
Term
A dependent t-test is used when the two groups of data are
Definition
related in some way. E.g. men 20-25 years of age compared to women 20-25 years of age.
Term
If two groups of data came from the same person, what kind of a statistical test would you use?
Definition
Dependent t-test.
Term
What statistical test would you use for two groups of data for pre and post test measures, or before vs. after treatment?
Definition
Dependent t-test.
Term
If you have more than two groups of data, you need to use a more sophisticated type of statistical analysis called
Definition
the Analysis of Variance or ANOVA.
Term
The ANOVA allows one to calculate
Definition
differences between and among groups.
Term
ANOVAs can be
Definition
one-way or one factor, two-way or two factors, or three-way or three factors.
Term
Factors
Definition
are the main effect that is being tested in an ANOVA.
Term
You have 1, 2 or 3 main factors in
Definition
an ANOVA that you want to calculate to determine differences between the groups.
Term
Statistical test for color preference for cars, trucks and SUVs would be
Definition
a one-way ANOVA
Term
A statistical test for high school vs. middle school students’ ratings for three types of video games would be
Definition
a two-way ANOVA.
Term
You determine the degree of freedom for independent samples or t-tests by
Definition
adding the number in each group and subtracting one from each group; eg if there are 20 people in each group for a total of 40 the df is 38.
Term
In independent samples for t-tests the number of subjects in the groups can be
Definition
different.
Term
Independent samples are
Definition
unrelated, uncorrelated.
Term
Dependent samples are
Definition
related, correlated.
Term
What type of t-test do you use when you have two measures from the same subjects or when subjects are matched according to some variables?
Definition
Dependent t-test.
Term
In a dependent t-test, the degrees of freedom are related to
Definition
the one pair of scores that is not free to vary.
Term
You determine the degree of freedom for dependent samples or dependent t-tests by
Definition
one less the number of pairs of scores; eg, if there are 20 in each group there are 20 scores so the df is 19
Term
In dependent samples for t-tests the number of subjects in the groups must be
Definition
the same.
Term
Examples of interval data are
Definition
attitude, ability, personality, intelligence, achievement tests, language tests, hearing thresholds
Term
Types of ratio data are
Definition
frequency counts, time and distance measures, latency of responses
Term
In data analysis, the type of data dictate
Definition
the type of analysis that can be performed.
Term
Data scales are also known as levels of
Definition
measurement.
Term
Nominal data involves
Definition
assigning a name or category to each item.
Term
Examples of nominal data are
Definition
=/- data, yes/no responses, normal/disordered, type of hearing loss, speech disorder, income levels, age groups, other demographic data
Term
Examples of ordinal data are
Definition
severity ratings, ratings or rankings by subject or others, voice quality ratings, levels of linguistic complexity
Term
In a two-way ANOVA there are two
Definition
independent variables (hence the name two-way).
Term
How many sets of hypothesis are there with the two-way ANOVA?
Definition
Three.
Term
The two independent variables in a two-way ANOVA are called
Definition
factors (denoted by A and B). The idea is that there are two variables, factors, which affect the dependent variable (Y). Each factor will have two or more levels within it, and the degrees of freedom for each factor is one less than the number of levels.
Term
The interaction effect is
Definition
the effect that one factor has on the other factor. The degree of freedom here is the product of the two degrees of freedom for each factor.
Term
There is an F-test for each of the
Definition
hypotheses.
Term
Assumptions of parametric tests are:
Definition
A. Scores are normally distributed
B. Sample size is reasonably large
C Interval or ration data are used
D. There is homogeniety of variance among groups of data
E. Subjects have been randomly sampled.
Term
Assumptions of Nonparametric tests are
Definition
A. Distribution free meaning distribution of scores does not fit the normal distribution pattern.
B. Sample size can be quite small.
C. Nominal or ordinal data can be used.
D. Lack of homogeniety; eg., two groups of data have large differences in variance
E. Subjects are selected using convenience or quota sampling
Term
The alternative hypothesis is the
Definition
hypothesis that is accepted when you reject the null hypothesis.
Term
Use of parametric and nonparametric allow reseachers to
Definition
make inferences about the population from the sample data.
Term
The one-way analysis of variance (ANOVA) is used to determine whether there are any significant differences between
Definition
the means of three or more independent (unrelated) groups.
Term
A one-way ANOVA is an omnibus test statistic and cannot tell you which specific groups were
Definition
significantly different from each other, only that at least two groups were. To determine which specific groups differed from each other, you need to use a post-hoc test.
Term
Why not compare groups with multiple t-tests instead of a one-way ANOVA?

Every time you conduct a t-test there is a chance that you will make a Type 1 error.
Definition
Every time you conduct a t-test there is a chance that you will make a Type 1 error. Better to miss a result than to conclude there is a meaningful difference.
Term
The t-test is only appropriate for situations where there are only
Definition
two levels of one independent variable.
Term
We use the term two-way or two-factor ANOVA,when the levels of
Definition
two different explanatory variables are being assigned, and each
subject is assigned to one level of
each factor.
Term
The ANOVA statistic is called the
Definition
F-test, after its developer, Fisher.
Term
Like the t, F depends on degrees of freedom to determine probabilities and critical values, but there is a difference between t and F in terms of the degrees of freedom concept. F has
Definition
two different degrees of freedom to calculate. In contrast, t has only one formula for calculating degrees of freedom.
Term
F-score or F-measure is a measure of a
Definition
test's accuracy.
Term
The assumption of homogeneity of variance is that the variance
Definition
within each of the populations is equal.
This is an assumption of analysis of variance (ANOVA).
Term
How will the alternative hypothesis chosen affect the critical values associated with t-test?
Definition
Because it raises or lowers the critical value according to whether it is nondirectional or directional.
Term
Which is a more serious error? Type l or Type ll?
Definition
Type l, because you used too high an alpha level.
Term
One-Way ANOVA has one
Definition
independent
variable (1 factor) with 2
conditions
– conditions = levels = treatments
– e.g., for a brand of cola
factor, the levels are:
• Coke, Pepsi, RC Cola
Term
Two-Way ANOVA has 2
Definition
independent variables (factors)
– each can have multiple conditions.
Term
We conduct Post-hoc Tests if
Definition
the ANOVA is significant–
at least one significant difference between conditions
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