Psychology Stats Exam 2 – Flashcards

Unlock all answers in this set

Unlock answers
question
A researcher is seeing if the level of satisfaction with college is different among students who participate in school activities compared to students who do not participate in school activities. Identify the dependent and independent variable in this study.
answer
IV: participation in activities, DV: level of satisfaction
question
What are the two hypotheses that you state in step 1 of the hypothesis testing procedure called?
answer
null hypothesis (h0), research hypothesis (h1)
question
Hypothesis testing is used with what general type of statistics?
answer
inferential
question
In step 2 of the hypothesis testing procedure you determine the characteristics of the comparison distribution. Which population is the comparison distribution: Population 1 or Population 2?
answer
population 2
question
To determine statistical significance you compare the z-score of your sample from Population 1 with what?
answer
cutoff sample scores/critical values; z-scores of % looked up in tail
question
Indicate whether you would use a one-tailed or two-tailed test for the following hypothesis: Netflix had fewer subscribers after they raised their prices.
answer
1-tailed
question
Why do researchers tend to use two-tailed tests rather than one-tailed tests?
answer
one-tailed test can make you miss a statistical significance if it on the other end of spectrum
question
State the following research hypothesis in symbols: Nebraska Wesleyan students have higher ACT scores than UNL students.
answer
u1 > u2
question
In which of the 5-steps of hypothesis testing do you indicate whether you test is one- or two-tailed?
answer
step 3
question
What type of distribution has more variance?
answer
distribution of individuals
question
A distribution of means is most likely to have what shape?
answer
normal
question
When your sample consists of a group of people (population 1) why can you not compare that to a distribution of individuals (population2)?
answer
because you must compare like with like and not groups to individuals
question
Which decision error is generally considered by researchers to be the more serious error
answer
type I
question
Why is there always the possibility when using statistics that our conclusions will be wrong?
answer
there is always some chance of error because we are never 100% sure
question
The significance level for a particular statistical test is .05. Which type of decision error will also have a 5% likelihood of occurring
answer
Type I
question
True or False? You can make both a Type I and Type II error in the same study?
answer
false
question
A psychologist who states the hypothesis that there will be no difference between a new approach to therapy and the standard approach is stating a
answer
null hypothesis
question
When a psychologist rejects the null hypothesis at the .05 level, the result of a study indicate that
answer
there is less than a 5% chance of getting such an extreme result by chance if the null hypothesis is true
question
A result is considered statistically significant when
answer
the sample score is so extreme that the null hypothesis is rejected
question
The decision to reject the null hypothesis using the Z test is made
answer
by comparing the Z score needed to reject the null hypothesis to the actual Z score of the sample
question
A psychologist who states the hypothesis that a new training program will be more effective than the old training program is stating a
answer
research hypothesis
question
How would a psychologist test the hypothesis that a new stress reduction program really works?
answer
try to reject the hypothesis that it does not work
question
The distribution that represents the situation in which the null hypothesis is true is
answer
the comparison distribution
question
If the cutoff Z score on the comparison distribution is +/- 2.31, a psychologist can reject the null hypothesis if the sample Z score on this distribution is
answer
2.83
question
When the results of a study are not extreme enough to reject the null hypothesis, a psychologist can conclude with reasonable confidence that
answer
the results are inconclusive
question
If a health psychologist wants to know if regular exercise improves peoples' health, the type of hypothesis the psychologist would use is
answer
one-tailed because the study is only interest in whether the exercise increases health
question
The correct argument for using a one-tailed test when there is a clear basis for predicting a result in a given direction is that
answer
it is less conservative in that one-tailed tests make rejecting the null hypothesis easier
question
A major misuse of significance tests is the tendency to
answer
decide that if a result is opposite to the prediction, the researcher can still do a two-tailed test later
question
A major misuse of significance tests is the tendency to
answer
decide that if a result is not significant, the null hypothesis is shown to be true
question
Which of the following statements is the most accurate description of hypothesis testing?
answer
it is a central theme in the statistical analysis of virtually all psychology research
question
When your sample is a group of people the correct comparison distribution to use is a distribution of means because
answer
comparing the mean of a sample to a distribution of individuals is a mismatch
question
In principal, a distribution of means can be formed by
answer
randomly selecting samples from a population, finding the mean of each sample, and then graphing the means
question
The mean of a distribution of means is
answer
the same as the original population mean
question
The variance of a distribution of means is smaller than the original population variance because
answer
extreme scores are less likely to affect a distribution of means
question
In general, the shape of a distribution of means tends to be
answer
unimodal & symmetrical
question
A study involving 10 participants has a known population mean of u=100 and variance of 25. Using the distribution of means, what characteristics of the comparison distribution would you report in Step 2?
answer
mean = 100, variance = 2.5
question
As the number of people in a sample gets larger, the distribution of means
answer
becomes a better approximation of the normal curve
question
Under what conditions is it reasonable to assume that distribution of means will follow a normal curve
answer
30 or more individuals involved or distribution of population means is normal
question
One important advantage of using effect sizes is that
answer
they are standardized scores that make comparisons of different studies easier
question
The alpha level is
answer
the probability of a type I error
question
If a study conducted at the .05 significance level has 80% power
answer
alpha = 5%, beta = 20%
question
In actual practice, the usual reason for determining power before conducting a study is
answer
to determine the number of participants needed to have a reasonable level of power
question
Type II errors concern psychologists because
answer
they could mean that good theories or useful practical procedures are not used
question
Setting the significance level cutoff .10 instead of the more usual .05 increases the likelihood of
answer
Type I error
question
Beta is the probability that
answer
if the research hypothesis is actually true, the experiment would still fail to support it
question
The statistical method currently used to combine the results of multiple studies is
answer
meta-analysis
question
A type I error is the result of
answer
incorrectly rejecting the null hypothesis
question
Power is the probability that
answer
if the research hypothesis is true, the experiment will support it
question
Failing to reject the null hypothesis when the research hypothesis is true is
answer
type II error
question
Effect size is
answer
the degree to which an experimental manipulation separates two populations
question
If the research hypothesis is true, but the study has a low level of power,
answer
the probability that the study will have a significant result is low
question
Cohen proposed effect size conventions based on the effects observed in psychology research in general because
answer
previously it was difficult to determine how large an effect size was
question
The conventional levels of significance of 5% and 1%
answer
are a compromise between the risk of making Type I and Type II errors
question
hypothesis testing
answer
procedure for deciding whether the outcome of a study supports a particular theory
question
hypothesis
answer
prediction, often based on informational observation, previous research, or theory that s tested in a research study
question
theory
answer
set of principles that attempt to explain one or more facts, relationships, or events; predictions are derived from theories
question
research hypothesis
answer
statement in hypothesis testing about the predicted relation between populations
question
Null hypothesis
answer
statement about a relation between populations that is the opposite of the research hypothesis
question
comparison distribution
answer
distribution used in hypothesis testing; represents the population situation if the null hypothesis is true
question
cutoff sample score
answer
in hypothesis testing, the point on the comparison distribution at which, if reached or exceeded by the sample score you reject the null hypothesis
question
conventional levels of significance
answer
p<.05, p<.01; levels of significance widely used in psychology
question
statistically significant
answer
conclusion taht the results of the study would be unlikely if in fact the sample population is no different from the general population
question
directional hypothesis
answer
research hypothesis predicting a particular direction of difference between populations
question
one-tailed test
answer
hypothesis-testing procedure for a directional hypothesis; region of comparison distribution in which the null hypothesis would be rejected is all on one side of the distribution
question
Nondirectional hypothesis
answer
research hypothesis that doesn't predict a particular direction of different between populations
question
Two-tailed test
answer
hypothesis-testing procedure for a nondirectional hypothesis; region of the comparison distribution in which the null hypothesis would be rejected is divided between the two sides of the distribution
question
distribution of means
answer
distribution of means of samples of a given size from a population; comparison distribution when testing hypotheses involving a single sample of more than one individual
question
mean of a distribution of means
answer
the means of a distribution of means of samples of a given size from a population; same as u
question
variance of a distribution of means
answer
variance of the population divided by the number of scores in each sample
question
standard deviation of a distribution of means
answer
square root of the variance of a distribution of means; aka SEM or SE
question
decision errors
answer
incorrect conclusion in hypothesis testing in relation to the real situation
question
Type I error
answer
rejecting the null hypothesis when in fact it is true
question
Alpha
answer
probability of making a Type I error; same as significance level
question
Type II error
answer
failing to reject the null hypothesis when in fact it is false
question
Beta
answer
probability of making a Type II error
question
Effect Size
answer
in studies involving means of one or two groups, measure of difference between populations
question
Effect size conventions
answer
standard rules about what to consider a small, medium, & large effect size, based on what is typical in psych research
question
Meta-analysis
answer
statistical method for combining effect sizes from different studies
question
Statistical power
answer
probability that a study will give a significant result if the research hypothesis is true
question
power tables
answer
table for a hypothesis-testing procedure showing the statistical power of studies with various effect sizes & sample sizes
question
Be able to explain the relationship between effect size and statistical significance in interpreting research results
answer
they are unrelated because effect size is how big the difference is between our means (practical significance) and statistical significance is if the is a difference between our groups (hypothesis testing; decision errors); power is related to both effect size and statistical significance
question
Independent variable
answer
what is being manipulated, predictor, cause
question
Dependent Variable
answer
what is being measured, what is being predicted, effect
question
Steps of Hypothesis Testing
answer
1. Identify populations & hypotheses 2. Determine population mean, population standard deviation 3. Determine cutoff sample score on comparison distribution at which the null hypothesis should be rejected 4. Determine your sample's score 5. Decide whether to reject the null hypothesis
question
p<.05 are what cutoff scores for 1-tailed & 2-tailed
answer
1.64 & 1.96
question
<0.2 effect size
answer
no effect
question
0.2-0.49
answer
small effect
question
0.5-0.79
answer
medium effect
question
>/= 0.8
answer
large effect
question
What determines power?
answer
sample size (larger sample increases power), effect size (larger effect size increases power), significance level (power is higher @.5), one vs. two-tailed test (varies power)
question
Use of power table
answer
determining # of participants before study, interpreting results of a study
question
low power with non significant results means
answer
truly inconclusive
question
high power with non significant results means
answer
unlikely that the research hypothesis is true or small effect
question
lower power with significant results means
answer
likely practical significance
question
high power with significant results means
answer
may not be practically significant
Get an explanation on any task
Get unstuck with the help of our AI assistant in seconds
New