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Statistics_Homework
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- Statistics
- Institution
- Buckinghamshire New University (London) (BNU)
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Q 5)Which of the following are the way(s) that the standard error of the difference between
sample means (denominator of the independent t-statistic) can be interpreted? (¼
Point)</strong>
A measure of the standard (average) distance between a sample statistic (M1 – M2) and the
corresponding population parameter (μ1 – μ2).
A measure of how much difference is reasonable to expect between two sample means if the
null hypothesis is true.
A measure of the error in Sample 1 only.
A measure of the error in Sample 2 only.
A measure of the standard (average) distance between a sample statistic (M1 – M2) and the
corresponding population parameter (μ1 – μ2) AND A measure of how much difference is
reasonable to expect between two sample means if the null hypothesis is true are correct.
Answer)
1) Measure of the average distance between a sample statistic
and the corresponding population parameter
However, if null is true, the population mean difference is zero; so we would be
measuring how close the sample mean difference is to zero; or measuring how
much difference there is between the means
Q 6)
If Sample 1 has 27 scores and Sample 2 has 21 scores what are the degrees of freedom for the
standard error of the difference between sample means
Answer)
Degrees of freedom of 2 samples = n1+n2-2 = 27+21-2 = 46
Q 7)
A sample of 27 individuals is measured under two different conditions (X1 and X2). What are
the degrees of freedom for the standard error of the difference between sample means?
Answer)
Degrees of freedom of 2 samples = n1+n2-2 = 27+27-2 = 52
Q 8)
Sixty-four participants are assigned to two conditions (X1 and X2) by matching the individuals
(32 matched pairs). What are the degrees of freedom for the standard error of the difference
between sample means?
, Answer)
Degrees of freedom of 2 samples = n1+n2-2 = 32+32-2 = 62
Q 9)
In order to use the independent-measures t-test, the population variances must be known?
Answer)
False, we will pick the variances from samples
Q10)
Which of the following are the assumptions that underlie the independent measures t-formula?
Answer)
There are two samples from two populations. (The samples can be different
sizes.)
The two samples are independent.
Both populations are normally distributed or both sample sizes are large enough
that the means are normally distributed.
(A rule of thumb is that the sample size is large enough if n ≥ 15.)
Both population standard deviations, σx and σy, are unknown, but are assumed to
be equal
All of these are correct assumptions underlying the independent measures t-
formula
Q 11) If the two populations from which the samples are selected do not have equal variances,
how does this affect the t-formula?
Answer)
It requires that the pooled variance must be used in the formula for the
standard error of the difference between means.
Q12) If there is a test to determine whether the two populations from which the samples were
selected have equal variances, what is the test?
Answer)
The F-Max test
When Hypotheses are about equal or unequal variances
we use F-Max test
, Q17)
In order to use the dependent-measures t-test, the population variances must be known?
Answer)
False as we require only the value in difference of Means.
Q18)
All other things being equal, what is the relationship between the standard error of the
difference between means for the dependent-measures design and the standard error of the
difference between means for the independent-measures design?
Answer)
Not sure..
Q19)
A study is conducted in order to examine the effects of two methods for teaching writing to
college students (Method 1 and Method 2). One-hundred college students taking a college
writing course are selected to participate. The 100 students are assigned to each method by
measuring each student’s IQ and creating 50 matched pairs. One student from each matched
pair is randomly assigned to Method 1 and one student from each matched pair is randomly
assigned to Method 2. Throughout the study, everything is held constant except for the IV
(Type of Method). This design is
Answer)
An Independent-measures design.
Reason i chosen is, 100 people are divided into 2 sample, Method 1 and Method 2
are Independent to each other &
The two samples are independent.
Both populations are normally distributed or both sample sizes are large enough
that the means are normally distributed.
(A rule of thumb is that the sample size is large enough if n ≥ 15.)
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