Study sets, textbooks, questions
Upgrade to remove ads
Psych 2220 - Exam 2St
Terms in this set (57)
The term ______ is used for the distribution of means in place of the term standard deviation
A z score of -1.0 is ___ compared to a z score of 2.0
Inferential Statistical test not based on assumptions about the population
inferential statistical test based on assumptions about a population
Under what conditions is it permissible to proceed with a hypothesis test even though the assumption that the population distribution is approximately normal is violated?
sample size greater than 30
What is standard error and how is it different from standard deviation
The standard error is smaller than the standard deviation of a distribution of scores
Which is an interval estimate based on the sample?
As the sample size increases, what happens to the test statistic?
Effect size is unaffected by the sample size
Interpret the following effect size, d =0.06
Going from a one-tailed to a two-tailed hypothesis test
Doesn't increase statistical power
Statistical power is the probability that we won't make a Type II error
Increasing statistical power
- increasing alpha
- increasing N-sample
- decreases standard deviation
- turning two-tailed hypothesis into a one-tailed hypothesis
- exaggerate the mean difference between levels of the independent variable
According to the ______ as sample size increases, the distribution of ____ assume a normal shape
the central limit theorem; sample means
A z-score is
the number of standard deviations a particular score is from the mean
95% confidence interval:
mLOWER = -1.96 (standard error) + mean
mUPPER = 1.96 (standard error) + mean
99% confidence interval
mLOWER = -2.58 (standard error) + mean
mUPPER = 2.58 (standard error) + mean
z(om)+mSAMPLE use sampke means + standard error
What is step 1 in hypothesis testing?
identify the populations, distribution, and assumputions
What is step 2 in hypothesis testing?
State the null and research hypothesis
What is step 3 in hypothesis testing?
Determine the characteristics of the comparison distribution (use the standard error equation)
What is step four in hypothesis testing?
Determine the critical values (cutoffs)
What is step five in hypothesis testing?
Calculate the test statistic
What is step six in hypothesis testing?
Make a decision
What is a one-tailed test?
What is a two-tailed test?
What are the assumptions for conducting analyses?
- The dependent variable is assessed using a scale measure
- The participants are randomly selected
- The distribution of the population of interest must be approximately normal (n<30)
What do you do when looking for scores as least as extreme to a z score in both directions
multiply the % in the tail by 2
What do you do when looking for the percentage of scores below the z score? (positive)
add the % mean to z to 50%
What do you do when looking for the percentage of scores below the z score? (negative) What about for percentage of scores above the z score?
subtract the % mean to z from 50%
add the % mean to z and 50%
the normal curve is a specific, mathematically defined curve that is _____________, __________, and _________.
bell-shaped, unimodal, and symmetrical
What does it mean to say that the normal curve is unimodal and symmetric?
Unimodal means there is one mode or high point to the curve. Symmetric means to the left and right sides of the curve have the same shape and are mirror images of each other
What is standardization?
a way to convert individual scores from different normal distributions to a shared normal distribution with a known mean, standard deviation, and percentiles
What is a z distribution?
a normal distribution of standardized scores
Why are z scores useful?
- they give us a sense of where a score falls in relation to the mean of its population
- they allow us to compare scores from different distributions
- they can be transformed into percentiles
What is a distribution of means?
a distribution composed of many means that are calculated from all possible samples of a given size, all taken from the sample population
What is standard error?
the standard deviation of a distribution of means
What does significantly significant mean?
if the data differ from what we would expect by chance if there were, in fact, no actual difference
What is an alpha?
the probability used to determine the critical values (cutoffs) in hypothesis testing
What is point estimate?
a summary statistic from a sample that is just one number used as an estimate of the population parameter
What is an interval estimate?
based on a sample statistic and provides a range of plausible values for the population parameter
What is a margin of error?
Statistical estimate of what the population looks like
-- How close your results are to actual population
What is effect size?
it indicated the size of a difference and is unaffected by sample size
How do you calculate effect size?
use the Cohen's d formula
What is Cohen's d?
a measure of effect size that assesses the difference between two means in terms of standard deviation, not standard error
What are Cohen's guidelines?
Small - 0.2 - 85% overlap
Medium - 0.5 - 67% overlap
Large - 0.8 - 53% overlap
As ____________ increases, the _______ becomes more extreme and it becomes easier to reject the null hypothesis
sample size, test statistic
Why are effect sizes rather than test statistics used when comparing study results?
Using effect sizes, which are not affected by sample size, rather than test statistics, which are influenced by sample size, ensures a fair comparison.
When alpha increases, both ________ and ________ increase.
power; probability of a Type I error
It becomes progressively easier to declare statistical significance as we increase:
A power analysis reveals that the study being run has low power. Which of the following methods is not an appropriate way to increase statistical power?
Increase the variance of the distributions.
We calculate a statistical power and find that it is 0.65. This means that if the null hypothesis is ________, we have a ________% chance of rejecting the null hypothesis.
The population mean for a standardized final exam in a course is an 83%. After taking a large sample from the new freshmen class, a 99% confidence interval of [84.81, 86.32] is calculated. If a 95% confidence interval were calculated based on the same data, it would _____ compared to the interval listed above.
be shorter (include less values)
The practical use of statistical power is that it informs you the researcher:
how many participants are needed to conduct a study that will produce quality data that you can trust.
What is statistical power?
a measure of the likelihood that we will reject the null hypothesis, given that the null hypothesis is false
The statement "It is hypothesized that children who attend an enrichment program will score higher on IQ tests compared to children who do not attend an enrichment program" best illustrates a:
a one-tailed test
If we reject the null hypothesis, the result is said to be:
A z test result of 4.12 would allow us to reject the null hypothesis, assuming we were conducting a two-tailed test with critical values of +1.96 and -1.96.
With which p-level, 0.05 or 0.01, is it easiest to reject the null hypothesis, and why?
It is easier to reject the null hypothesis at the 0.05 level, because it has a larger critical region.
Other sets by this creator
Psych 2220 Final Exam - Dr. Yocom OSU
Recommended textbook solutions
The Practice of Statistics for the AP Exam
Daniel S. Yates, Daren S. Starnes, David Moore, Josh Tabor
David E. Bock, Paul Velleman, Richard D. De Veaux
Statistics for Engineering and the Sciences, Volume 1
Terry Sincich, William Mendenhall
Business Statistics in Practice: Using Data, Modeling and Analytics
Bruce Bowerman, Emily Murphree, Richard O'Connell
Other Quizlet sets
HS MSSN 11
Social Psych Chapter 4
Tobacco True/False Quiz
sociology deviance test