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biostats
biostats test 2
67
Nursing
Graduate
07/07/2012

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Cards

Term
a particular change or outcome that does not appear to be due to chance is what?
Definition
statistical significance
Term
for the value of p to be found outside the dotted lines, this dotted line is termed the ___________
Definition
critical region
Term
for a result to be termed statistically significant in must lie where?
Definition
at or outside the limits or the critical region
Term
the critical region is chosen by the investigator and indicated by what?
Definition
greek letter alpha     α
Term
H is one or two tailed?
Definition
null hypothesis and it is two tailed  b/c doesn't state where difference is , just that there is a difference
Term
Hd is used with 1 or 2 tailed tests?
Definition
1 tailed tests
Term
hypothesis testing for Ho
Definition

1. ID the hypothesis

2. set up the null hypothesis

3.  perform statistical test

4.  if p≤a there is a statistical significance

5.  the null hypothesis Ho is rejected

6. the alternative hypothesis Ha is accepted

Term
for a null hypothesis a one or a 2 tailed test is used?
Definition
a two tailed test
Term
for a null hypothesis test if p≤alpha it is statistically sig and what happens?
Definition
Ho is rejected
Term
hypothesis testing for Hd
Definition
  1. identify research hypothesis
  2. set up the directional hypothesis Hd
  3. perform statistical test
  4. if p≤alpha there is a statistical significance
  5. the directional hypothesis Hd is not rejected 
Term
for a directional hypothesis what type of test is used?
Definition
1 tailed
Term
in directional hypothesis if p ≤ alpha , the results are statisitically sig. what do you do?
Definition

do not reject the Hd

Term
a type 1 error is a ______ _______
Definition
false positive
Term
rejecting the Null when it should not be rejected is called a type_____ error because
Definition
type 1-  larger the alpha the larger the chance for type 1 error ex. if alpha 0.05 then 5 times in 100 you will find differences, stricly due to chance)
Term
failure to reject the null when it should be rejected is a type ____ error, why?
Definition
type 2, there is a statisically significant difference, it is represented by β=1-α 
Term
any characteristic that is randomly distributed in a population is described by a __________ _________
Definition
normal distribution
Term
the data in a normal distribution are almost always ___ or ___
Definition
interval or ratio level data
Term

in a normal distribution

y axis (vertical)--?

x axis (horizonatal)--?

Definition

y-frequency (which increases for the bottom, the origin, to the top)

x - magnitude ( which increases from the origin to the right)

 

 

Term

in any normal distribution____% is found between 1 and -1 standard deviation

___% from 2 to -2

___ for 3 to -3

 

Definition

68%

 

95%

 

>99%

 

Term
probability formula
Definition
number of desired outcomes/total possible outcomes
Term
the mean of a sampling distribution will be the same as the ______ ______
Definition
population mean
Term
the outcomes that occur rarely will fall where is a z or a t distribution?
Definition
in the tails
Term
what does the central limit theorem state?
Definition
if we draw equally sized samples from a non-normal distribution, the distributions of the means of these samples will still be normal, as long as the samples are large enough
Term
how does a researcher set a level of significance?
Definition

it involves determining a level of probability where the researcher feels the results would happen only rarely strictly due to chance

 

Term
α is most commonly set at ?, meaning what?
Definition

0.05;  meaning the probability of obtaining similar results strictly due to  chance is 5 times or less in 100.

 

Term

as α increases what type of error

as decreases?

α=?

Definition

as increases-type 1

as decreases-type 2

α= 1-β

Term
discuss bell shape for small n verses lg n.
Definition

the smaller the n the, the flatter the bell shaped curve, and therefore the larger the standard error of the mean

as the n increases the SEM decreases and the bell shaped curve begins to more closely resemble the normal curve

Term
formula for SEM
Definition

SEM=

 

s

 ____

 

√n

Term
t tests are used
Definition
  1. used to compare (the differences between) 2 means
  2. used for interval or ratio level data
  3. used to estimate the probability of obtaining a similar difference between means stricly due to chance 
Term
three common forms of the t test
Definition

one sampled

paired-samples

independent

Term
one sample t test
Definition
compares a sample mean (¯X) to a population mean (μ) where df= n-1
Term

paired t-test

 

Definition

compares 2 sample means gathered from the same subjects where df= n-1

 

Term
independent t tests
Definition
samples t test that compares sample means form 2 different gorups of subjects were df=n-2
Term
in order to use t tests what are the assumptions that should be met?
Definition
  • compare only 2 sets of scores
  • use interval or ratio level data
  • homoscedascity (equality of variences of the sample groups) for the independent t test
Term
what does levines test do?
Definition
assesses equality of variences and that if p or sig. for the vlaue of F is >0.05 you can assume equality of variences and use the upper line in SPSS output, if the sig or p ≤0.05 for levene's test you cannot assume equality of variances and must use that line in the spsss
Term
by increasing sample size the variability should ______
Definition

decrease

 

Term
increasing power requires a ____ sample size
Definition
increased
Term
a small sample size often results in vulnerablility to what?
Definition
type 2 error
Term
small effect requires large ___
Definition
n
Term
if you are examining 2 sampling distributions which have the same mean, but a different standard error of the mean (SE). the distribution with the smalle SE will likely have a large or a small sample size?
Definition
larger
Term

an effect size (d) is considered small

0.2

0.3

0.4

 

Definition
0.2
Term

use ____ to compare 2 means

but use_____ to compare more than 2 means

 

Definition

use t tests-2 means

use ANOVA for more than 2

Term
if you use t tests to evaluate more than 2 means you increase the likelihood of what?
Definition
type 1 error
Term

answer with t and z

 

the value of ___ locates the position of a socre on a distribution (for a population), while the value of ___ locates the position of a diferencein sample means on a distribution of sample means.

Definition

1. z

2. t

 

Term
a t-test is used to compare ___ mean scores
Definition
2
Term
to calculate df formula?
Definition
n-1
Term
what is the appropriate test for to O X O design if one has interval level data and 15 subjects?
Definition
t test for paured or correlated measures
Term
to test for mean differences between 2 groups use what test?
Definition
t test for independent samples
Term
when the p is 0.046 and the alpha is 0.5 then should the null hypothesis be rejected or accepted
Definition
reject the null
Term
what procedure can be used to reduce type 1 error if more than 2 groups are compared using t tests (as in post hoc comparisons) it consists of calculating an adjusted alpha by dividing the original alpha by the # of comparisons made
Definition
Bonferroni correction
Term
ANOVA stands for
Definition
analysis of variance
Term
ANOVA is a comparison of variance associated with the____________________ _______________ compared to variance of____________ _______________
Definition
independent variable vs. random variation
Term

in anova the independant variable is __________

and the dependent variable is _________ or _____

Definition

ind- categorical

dep- interval or ratio

Term

variance associated with the independent variable is termed_________ ______________ variance or ____________ variance

or _______________

Definition

between groups or explained

Sum of Squares between or SS between

Term

variance associated with random variation is termed __________  ______ variation or

 _____________ variance or ______

also SS___ or SS__

Definition

within group variance

unexplained variance

variance of error

SSwithin or SSerror

Term
total variance =________+_________
Definition
total variance= within group variance+between groups variance
Term
the anova utilizes what test?
Definition
F-test
Term
F=
Definition

F= mean squares between

____________________

mean squares within

Term

formula for MSbetween

 

 

Definition

MSbetween=SSbetween

                  ------------

             df

 

where df=(k-1)

k is # of groups which are the levels of categories of the independent variable

Term
formula for MSwithin
Definition

MSwithin= SSwithin

                         ------------------

         df

 

where df= k(n-1) where k is the # of groups which are the levels of categories of the ind. variable and n is the number within each group

Term
the higher the f, the ____ the probability of obtaining similar results strictly due to chance
Definition
lower
Term
ANOVA or the F test provides a statistical test for what many call the ______ _______, that states what?
Definition
omnibus hypothesis- there will be no stat. sig. difference in means of groups 1, 2, 3, etc
Term
an obtained F that is statistically sig (< 0.5) tells you what?
Definition
that at least one group is SSD from the others
Term
if the f test is SSD must do what?
Definition
post hoc test to acertain where the differences are. if all groups are diff from each other, or which sets of groups are diff.
Term
what does the f anova compare?
Definition
the effects of more than 1 ind. variable on one dependent variable ex. examining exercise programs wts, running etc and gender M vs F on BMI
Term

1.in an F anova the explained or between groups variance is ________ among the ind. variables

2.  the variance explained by each independent variable individually is called a ____ ____

3.  the variance explained by the independent variable together is called an ______

 

Definition

1.partitioned (attributed)

2.  Main effect

3.  interaction

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