Stats Exam 2
You have a population with μ=40 and a variance (note this is a variance not a standard deviation) of σ²=16. Compute the standard score for a score of Y=45 compared to other scores in the population.
1.25
What value of z gives a one-tail p value of .05 on the upper tail? z = ?
1.65
What values of z give a two-tail p value of .05 (.025 on each tail). z = ± ___? (Input the positive value)
1.96
As the standard deviation of the population from which we sampled is not known, we will need to estimate it. The sample is repeated again below, along with the SS of the sample. Begin by estimating the variance of the population from which we sampled. Y= 38, 39, 42, 44, 46 M=41.8 SS=44.80 est. σ2=?
11.2
You repeatedly sample 15 scores from a population that is normally distributed with μ=230 and σ=50. What will be the standard deviation of the sample means (assuming you drew an infinite number of samples each with N=15)?
12.91
You sample 15 scores from a population that is normally distributed with μ=230 and σ=50. State the value of the standard error of the SDM. σM = ?
12.91
Input the percent in question from the following image of a normal curve. Use the values given in the text from a similar sort of curve, do not include the % sign in your answer (Canvas expects a number). Percent = ____%
13.59
In a population that is normally distributed, what PERCENT of the scores will fall between z=-.40 and z=.40? This question is just to make sure you can go from proportion to percent. Do not include the percent sign, Take the answer to the full decimal places available. percent = __%
31.08
Input the percent in question from the following image of a normal curve. Use the values given in the text from a similar sort of curve, do not include the % sign in your answer (Canvas expects a number). Percent = ____%
34.13
We are sampling from a population that has 𝝁=40, what would be the average value of the sample means drawn from that population? In other words, 𝝁M=?
40
Which of the following confidence intervals provides a more precise idea of the effect of the independent variable in some experiment?
5.1 ≤ μ1-μ2 ≤ 8.9
Will we now move away from the data above and talk about confidence intervals in general. Which of the following confidence intervals provides a more precise idea of the plausible values of μ?
55 ≤ μ ≤ 58
If a population is normally distributed, with μ=150 and σ=10, we know that approximately ____% of the scores fall between 140 and 160. Give the approximate answer, do not include the percent sign.
68
For all normal curves, ____% of the scores fall within 1 standard deviation of the mean (go to two decimal places, do not include the % sign).
68.26
Estimate the standard deviation of the following curve.
7
If a population is normally distributed, with μ=150 and σ=10, we know that approximately ____% of the scores fall between 130 and 170. Give the approximate answer, do not include the percent sign.
95
For all normal curves, ____% of the scores fall within 2 standard deviations of the mean (go to two decimal places, do not include the % sign).
95.44
If a population is normally distributed, with μ=150 and σ=10, we know that over ____% of the scores fall between 120 and 180. Give the approximate answer, do not include the percent sign.
99
For all normal curves, ____% of the scores fall within 3 standard deviations of the mean (go to two decimal places, do not include the % sign).
99.74
In experiment one (which had 8 scores), t(6)=2.04, p=.0874 In experiment four (which had 16 scores), t(14)=3.11, p=.0077 Which experiment had more power (assuming the IV really did have an effect)?
Experiment Four (N=16)
In experiment one, t(6)=2.04, p=.0874 In experiment five (which had much less variance among the scores within each group), t(6)=5.20, p=.0020 Which experiment had more power (assuming the IV really did have an effect)?
Experiment five(less variance)
Timmy comes home from school with grades from exams in the following subjects: Math Y=145, z=-1.89 English Y=32, z=2.5 Geography Y=10, z=0.2 In which class did he do very poorly compared to other students in the class?
Math
If the populations are not normally distributed and the population variances are not equal then...
Neither the standard t test nor Welch's will work well
If our decision is to 'not reject H0' can we conclude that H0 is true?
No
If our decision is to 'not reject H0' can we conclude that the independent variable had no effect?
No
We are sampling 15 scores from a population, can we reasonably count on the SDM being normally distributed?
No
In which of the following samples did the scores differ more from each other? Assume there is no outlier affecting the measures.
Sample One: S=5.24
In which of the following samples did the scores differ more from each other? Assume there is no outlier affecting the measures.
Sample Two: S=741
The distribution of all the sample means you could obtain if you sample a specific number of scores from a specific population is called the________ __________ of the __________
Sampling distribution of the mean
In the empirical approach why do you have to sample with replacement?
So that you sample from the same population each time
Which of the following are attributes of a correlational design?
Subjects are not randomly assigned to groups The independent variable is not manipulated by the experimenter.
Which of the following are attributes of a true experimental design?
Subjects are randomly assigned to groups The independent variable is manipulated by the experimenter.
What has to be true for the empirical approach to work?
That you sample with replacement
You sample with replacement from a card deck of unknown composition (i.e. this is not a normal deck of cards). In 30 samples you obtained five queen of hearts. What is the probability of drawing a queen of hearts?
0.17
In a population that is normally distributed, what proportion of the scores will fall at least 1.16 standard deviations away from the mean (in either direction)?
0.246
You are going to sample from a population that is normally distributed with μ=65 and a σ=9, if you sample six scores from the population what is the probability that the sample mean will be at least 4 away from the population mean in either direction, in other words, p(M≤61 or M≥69)=? (It would be an excellent idea to draw a curve and to show the formulas and your computations.)
0.2758
You have a bag of marbles consisting of 10 yellow, 5 green, 12 black, and 13 red marbles. Each marble has an equal chance of being selected. What is the probability you will draw a black marble? p(A)=
0.3
In a population that is normally distributed, what PROPORTION of the scores will fall between z=-.40 and z=.40? Take the answer out to the full decimal places available in the probability tool.
0.3108
You are going to sample from a population that is normally distributed with μ=65 and σ=9, if you sample one score from the population, what is the probability that it will be at least 4 below the population mean, in other words, p(Y≤61)=? (It would be an excellent idea to draw a curve while working this out.)
0.33
In a population that is normally distributed, what proportion of the scores will fall 0.40 or more standard deviations below the mean (i.e. z ≤ -0.40).
0.3446
If you are sampling from a population where 40% of the people own bicycles then the probability of any one person you randomly select owns a bicycle would be _____? State the probability as a proportion.
0.4
We have a population of scores that is normally distributed with a mean of μ=350 and a standard deviation of σ=20. What proportion of the scores fall within ±17 of the mean (i.e. 333 ≤ Y ≤ 367)? Recommendation: draw the population and shade in the regions. State answer to four decimal places.
0.6047
If event A is defined as drawing a red marble from a bag of marbles, and p(A)=0.35, then p(~A)=?
0.65
If p(A)=0.25, then p(~A)=
0.75
In a population that is normally distributed with a mean of 66 and a standard deviation of 5, what proportion of the scores will fall within ±7 of the mean (i.e. 59 ≤ Y ≤ 73)?
0.8385
We sample 8 scores from a population that is normally distributed with a mean of μ=350 and a standard deviation of σ=20. What proportion of the sample means will fall within 17 of the population mean (i.e. 333 ≤ M ≤ 367)? Recommendation: draw the SDM and shade in the regions. Answer to four decimal places.
0.9836
power + beta =
1
The researcher is simply testing to see if reaction times to the two different type of stimuli differ, she is not testing a theory which predicts which stimulus should have the faster reaction times. Should the data be analyzed using a two-tailed test or a one-tailed test?
Two-tailed
If H0 is true, what is the probability that your data will lead you to incorrectly decide to reject H0? In other words, the probability of making a Type 1 error when H0 is true is called....
alpha
Once you decide upon a significance level that also sets the value of ______.
alpha
Which of the following statements is (are) correct?
alpha is the probability that if H0 is true that we will incorrectly decide to reject H0
The hypothesis you hope to prove, the one that proposes that real differences exist, that the data are not simply due to random sampling error, is called the _________ hypothesis.
alternative
That the average of the sample means equals the mean of the population from which the samples were drawn is why the sample mean is __ ______ _______ of the population mean.
an unbiased estimate
A normal curve is shaped like a _______.
bell
If H0 is false, what is the probability that your data will lead you to incorrectly decide to not reject H0? In other words, the probability of making a Type 2 error when H0 is false is called....
beta
If in reality H0 is false and your data lead you to reject H0, what would that be?
a correct decision
If in reality H0 is true and your data lead you to not reject H0, what would that be?
a correct decision
If your decision is to 'reject H0', what does that imply about Ha?
accept Ha
A variable (something other than random error and the independent variable) that could account for why the group means differ is called a _________ variable.
confounding
A researcher wants to know what leads to better physical conditioning, downhill skiing or cross-country skiing. At the end of the winter she asks for volunteers who have only been downhill skiing during the winter and for volunteers who have been only cross country skiing during the winter. The physical conditioning of each volunteer is then measured. What type of experimental design is this?
correlational design
When determining cause and effect relationships between variables, the variable that you think will be the cause is called the ...
independent variable
According to the author, the main problem in using the mean to describe a group is that
it ignores the individual differences of the people within the group
To say that two events can't both happen is to say that they are __________ ____________ events.
mutually exclusive
Event A and Event ~A are:
mutually exclusive and exhaustive
The null and alternative hypotheses are always:
mutually exclusive and exhaustive
The two hypotheses (H0 and Ha) are
mutually exclusive and exhaustive
'~A' represents.
not A
Which of the following are the only two possible (official) results of an experiment?
reject H0 do not reject H0
When running an experiment what we actually have to base our decision upon are...
samples
How improbable the results have to be to reject H0 is called your
significance level
Now it is time to put the standard deviation on the curve, in this case it is the standard deviation of the possible values of (M1-M2). This is also known as the _______ _________
standard error
Now it is time to put the standard deviation on the curve, in this case the standard deviation of the possible values of (M1-M2). This is also known as the ________ _________
standard error
The standard deviation of the SDM is also known as the
standard error
The score that reflects how many standard deviations above or below the mean a particular score falls is called the _________ __________ .
standard score
Because we have to estimate the standard deviation (standard error) this means that the sampling distribution will be a '__' distribution rather than a 'normal' distribution. (don't input the '' signs).
t
If the null hypothesis proposes that two samples come from populations that have identical means, then which would be more probable?
that the two sample means will be similar in value
Which of the following is an assumption underlying the t test for independent groups?
the 2 populations are normally distributed
If you have a confounding variable in your experiment and you reject H0 then..
you don't know whether the independent variable, the confounding variable or both caused the groups to differ
The assumption of normal populations can be (somewhat) safely violated if....
you have a large N in each group
If the null hypothesis is true, then the average (mean) value of M1-M2 should equal...
zero
If μ1 - μ2 ≠ 0 which of the following do we conclude (assuming no confounding variables)
the independent variable has an effect
If μ1 - μ2 = 0 which of the following do we conclude (assuming no confounding variables)
the independent variable has no effect
M1 - M2 ≠ 0. What can we conclude from that (without further analysis)?
the samples had different means
Which of the following is an assumption underlying the t test for independent groups?
the scores are independent of eachother
Which of the following is an assumption underlying the t test for independent groups?
the two populations have the same variance
If the two populations have identical means:
the two sample means will probably differ at least a little due to random sampling error
The previous three probabilities were determined using the:
theoretical approach
A researcher wants to know what leads to better physical conditioning, downhill skiing or cross-country skiing. She obtains 30 volunteers who do not know how to ski and randomly divides them into two groups. One group is taught how to downhill ski and subsequently go skiing 20 times during the winter, the other group is taught how to cross-country ski and they go skiing 20 times during the winter. At the end of the winter the physical conditioning of each student is measured. What type of experimental design is this?
true experimental design
The t test for two independent groups is an appropriate tool to use to analyze your data when you want to determine whether:
two populations have different means
In the previous question: "You are going to sample from a population that is normally distributed with μ=65 and a σ=9, if you sample six scores from the population what is the probability that the sample mean will be at least 4 away from the population mean in either direction, in other words, p(M≤61 or M≥69)=?" What type of probability is that?
two-tail p value
How seriously is the validity of the t test threatened when the assumption of independence is violated?
very seriously
If the 95% confidence interval of the effect size is: 2.89 ≤ μ1-μ2 ≤ 9.1, would we reject H0?
yes
Which of the following is the mean of the curve?
μ(M1-M2)=0
If the independent variable has an effect, then which of the following hypotheses would be true?
μ1 - μ2 ≠ 0
In some experiment M1=100 and M2=75, you analyze the data using a one-tailed test which predicted that μ1>μ2 and the results are statistically significant (i.e. you reject Ho). Which of the following can you conclude?
μ1>μ2
In some experiment M1=100 and M2=75, you analyze the data using a two-tailed test and the results are statistically significant (i.e. you reject Ho). Which of the following can you conclude?
μ1≠μ2
In some experiment M1=23 and M2=1750, you analyze the data using a one-tailed test which predicted that μ1>μ2 and the results are not statistically significant (i.e. you do not reject H0). Which of the following can you conclude?
μ1≤μ2
Which of the following is the symbol for the mean of the SDM?
μM
Which of the following is the symbol for the standard deviation of the SDM?
σM
Now estimate the standard deviation of the population from which we sampled. Y= 38, 39, 42, 44, 46 M=41.8 SS=44.80 est. σ=?
3.35
The general rule of thumb for how large N needs to be for us to count on the SDM being normally distributed is for N to be ≥ ____
30
The t test has its most serious problems when
Both assumptions are violated in the same data
We are sampling 5 scores from a population that is normally distributed, can we reasonably count on the SDM being normally distributed?
Yes
You sample 15 scores from a population that is normally distributed with μ=230 and σ=50. Can you count on the SDM being normally distributed?
Yes
The abbreviation for the sampling distribution of the mean is the '____'.
SDM
Where are we going to get the value for the standard error?
By estimating it from our data
Timmy comes home from school with grades from exams in the following subjects: Math Y=145, z=-1.89 English Y=32, z=2.5 Geography Y=10, z=0.2 In which class did he do very well compared to other students in the class?
English
What has to be true for the theoretical approach to work?
Every possible event has an equal chance of occurring
Look at the curve and estimate ('eyeball') the standard score for a score of 60 in that population.
-0.5
Using the formula for z, compute the standard score for a score of 60 in the population.
-0.56
What value of z gives a one-tail p value of .01 on the lower tail? z = ?
-2.33
In a population that is normally distributed with a mean of 66 and a standard deviation of 5, what proportion of the scores will be at least 7 away from the mean in either direction (i.e. Y<= 59 or Y>=73)?
0.1615
When expressed as a proportion probability will always be a value between ___ and ____.
0 and 1.00
When expressed as a percent probability will always be a value between ___% and ____%.
0 and 100
We sample 8 scores from a population that is normally distributed with a mean of μ=350 and a standard deviation of σ=20. What proportion of the sample means will be at least 17 above the population mean (i.e. M ≥ 367)? Recommendation: draw the SDM and shade in the regions. Answer to four decimal places.
0.0082
We sample 8 scores from a population that is normally distributed with a mean of μ=350 and a standard deviation of σ=20. What proportion of the sample means will be at least 17 below the population mean (i.e. M ≤ 333)? Recommendation: draw the SDM and shade in the regions. Answer to four decimal places.
0.0082
We sample 8 scores from a population that is normally distributed with a mean of μ=350 and a standard deviation of σ=20. What proportion of the sample means will be at least 17 away from the population mean in both directions (i.e. M ≤ 333 or M≥367)? Recommendation: draw the SDM and shade in the regions. Answer to four decimal places.
0.0164
What is the probability of drawing a 'one-eyed jack' from a deck of cards (there are two 'one-eyed' jacks in a deck of 52 cards)? p(A)=
0.04
Consequently in psychological experiments, the probability that you will reject H0 when the H0 is actually true =
0.05
In psychology the most commonly used value for the significance level is _____
0.05
What is the probability of drawing a jack from a deck of cards (there are four jacks in a deck of 52 cards)? p(A)=
0.08
In a population that is normally distributed with a mean of 66 and a standard deviation of 5, what proportion of the scores will be at least 7 above the mean (i.e. Y≥73)?
0.0808
In a population that is normally distributed, what proportion of the scores will fall 1.3 standard deviations or more above the mean (i.e. z ≥ 1.3)?
0.0968
Input the percent in question from the following image of a normal curve. Use the values given in the text from a similar sort of curve, do not include the % sign in your answer (Canvas expects a number). Percent = ____%
0.13
You are going to sample from a population that is normally distributed with μ=65 and a σ=9, if you sample six scores from the population what is the probability that the sample mean will be at least 4 below the population mean, in other words, p(M≤61)=? (It would be an excellent idea to draw a curve and to show the formulas and your computations.)
0.1379
Input the percent in question from the following image of a normal curve. Use the values given in the text from a similar sort of curve, do not include the % sign in your answer (Canvas expects a number). Percent = ____%
2.15
What value of z gives a one-tail p value of .01 on the upper tail)? z = ?
2.33
You sample 15 scores from a population that is normally distributed with μ=230 and σ=50 and you write down the mean of that sample. You then repeat this an infinite number of times, each time sampling 15 scores from that population and noting the mean of the sample. What will be the average (mean) value of those sample means?
230
You sample 15 scores from a population that is normally distributed with μ=230 and σ=50. State the value of the mean of the SDM. μM = ?
230
Estimate the standard deviation of the following curve.
3.2
When you roll a six-sided die every face (1,2,3,4,5,6) has an equal chance of occurring. Define event A as rolling a '2' and event B as rolling a number that is below '4'. We found in the previous questions that p(A)=0.17 and p(A|B)=0.33, what if anything does that tell you about whether A and B are independent?
A and B are not independent
Which of the following will have the greatest power?
A one-tail test when the theory's prediction is correct
If in reality H0 is true and your data lead you to reject H0, what would that be?
A type 1 error
If in reality H0 is false and your data lead you to not reject H0, what would that be?
A type 2 error
In some other scenario, p(C)=0.8, p(C|D)=0.8 , what if anything does that tell you about whether C and D are independent?
C and D are independent
The theorem that states the SDM will be normally distributed if N is large enough is called the _________ _________ Theorem
Central Limit
Which of the following will increase the power of the experiment?
Decreasing the variability of the scores within each group
Now let's say that the researcher is testing a theory which predicts that reaction times should be faster (i.e. smaller) to auditory stimuli than to visual stimuli. What type of hypothesis is being tested?
Directional hypothesis
Let's say that M1=50 and M2=61 and the two-tailed p value is p=.09 For the two-tailed test, what would you decide?
Do not reject H0
M1=50 and M2=61 and the two-tailed p value is p=.09 For a one-tailed test of a theory which predicts that μ1 should be greater than μ2, p=.995, what is your decision?
Do not reject H0
Which of the following will lead to more precise confidence intervals?
Drawing a large sample AND Drawing from a population that has a small variance
If event A is defined as the probability of drawing a black card from a normal deck of 52 cards, then p(~A) would be the probability of...
Drawing anything but a black card
Which of the following is the symbol for the null hypothesis?
H0
The researcher is testing a theory which predicts that reaction times should be faster (i.e. smaller) to auditory stimuli than to visual stimuli. Which of the following is the correct Null hypothesis for this one-tailed test?
H0: μa≥μv
Which of the following would be appropriate ways of writing the null hypothesis?
H0: μupper = μlower H0: μ1 = μ2
Which of the following is the symbol for the alternative hypothesis?
Ha
Which of the following would be appropriate ways of writing the alternative hypothesis?
Ha: μ1 ≠ μ2 Ha: μupper ≠ μlower
The researcher is testing a theory which predicts that reaction times should be faster (i.e. smaller) to auditory stimuli than to visual stimuli. Which of the following is the correct ALTERNATIVE hypothesis for this one-tailed test? In the following options 'a' stands for 'auditory' and 'v' for 'visual'.
Ha: μa<μv
Which of the following would lead to a more precise confidence interval of the effect size?
Increase the size of the samples Select a dependent variable that has less variance
Which of the following will increase the power of the experiment?
Increasing N
Which of the following will increase the power of the experiment?
Increasing the effect of the independent variable
When the occurrence of one event makes it neither more nor less probable that the other event will occur as well then the two events are said to be ____________ .
Independent
The 95% confidence interval is: 21.80 ≤ μ ≤ 37.69 Which of the following is the correct interpretation of this confidence interval?
It provides a range of plausible values for μ given our data.
What effect does a large amount of variability in the population have on the probability of getting a representative sample?
Makes it harder
What effect does a large amount of variability in the population have on the probability of getting a representative sample?
Makes it less likley
What effect does a large amount of variability in the population have on the probability of getting a nonrepresentative sample?
Makes it more likley
We randomly sample five scores from a population that is normally distributed with a mean of 40 (i.e. 𝝁=40). Y= 38, 39, 42, 44, 46 M=41.8 Our sample mean was 1.8 above the population mean. We want to determine the probability that we would have obtained a sample mean that is 1.8 or more away from the population mean (in either direction). In other words p(M ≤ 38.20 or M ≥ 41.80). To do this we need to look at all of the sample means we might obtain (i.e. the SDM) if we sample five scores from that population. Is the standard deviation of the population given in this story problem?
No, so we will need to use the t distribution.
The researcher is simply testing to see if reaction times to the two different type of stimuli differ, she is not testing a theory which predicts which stimulus should have the faster reaction times. What type of hypothesis is being tested?
Nondirectional hypothesis
The researcher is testing a theory which predicts that reaction times should be faster (i.e. smaller) to auditory stimuli than to visual stimuli. Should the data be analyzed using a two-tailed test or a one-tailed test?
One-tailed
The various approaches to increasing the power of the experiment will increase our chances of rejecting H0
Only if H0 is actually false
The various approaches to increasing the power of the experiment will increase our chances of proving our independent variable had an effect
Only when the independent variable really does indeed have an effect
Which of the following are attributes of a quasi-experimental design?
The independent variable is manipulated by the experimenter. Subjects are not randomly assigned to groups.
p(A|B) is read as...
The probability of event A given event B
So for our sample: est. μ = 29.75 and our 95% confidence interval is: 21.80 ≤ μ ≤ 37.69 (depending on how you rounded). Which of the following is the correct interpretation of this confidence interval?
There is a 95% chance that the confidence interval captures the true value of μ
If the assumption that the populations have the same variance is violated then the best approach is to...
Use Welch's version of the t test
Which would give you, on the average, less error in using the sample mean to predict the population mean?
When the standard deviation of the SDM equals 2
Which would give you, on the average, more accuracy when using the sample mean to predict the population mean?
When the standard error of the SDM (i.e. σM) = 5.3
When do we have to use the "t distribution" rather than a "normal distribution" to get the correct "p values"?
When we have to estimate the standard deviation of the population.
In which of the following two samples would the variance and standard deviation not do a very good job of describing the variability of the scores?
Y = 3, 80, 80, 80, 80, 80
One study of the heights of trees in a forest used inches as the measure of height, another study of the very same trees used feet as the measure of height. Would the two studies arrive at different values for the standard deviation?
Yes
We are sampling 40 scores from a population, can we reasonably count on the SDM being normally distributed?
Yes
In an experiment, which of the following would be a justification for making the test one-tailed (that μ1 < μ2).
You are testing a theory which specifically predicts that M1 should be less than M2 Some previous, similar, experiment found that M1 < M2
'Power' is the probability that...
You will be able to Reject H0 when H0 is actually false
Another way of saying that is that 'power' is the probability that...
You will be able to conclude your independent variable had an effect when it actually did
When determining cause and effect relationships between variables, the variable that you think will be the affected by the other variable is called the
dependent variable
The previous probability was determined using the
empirical approach
Say that you are flipping a fair coin, one that has an equal chance of coming up heads or tails, and by some freakish chance you happen to get 20 heads in a row. What is the probability that the next flip will also be a head?
equal to .50 as the tosses of the coin are independent
To say that the definition of two events cover every possible event that could occur would be to say that the events are ______________.
exhaustive
Timmy comes home from school with grades from exams in the following subjects: Math Y=145, z=-1.89 English Y=32, z=2.5 Geography Y=10, z=0.2 In which class did he do about average compared to other students in the class?
geography
This particular t test will only be appropriate when everyone's scores are completely unrelated to everyone else's scores, which is to say that the scores are __________.
independent
In null hypothesis testing you start by determining the probability of having obtained your data if the ________ hypothesis were true.
null
The hypothesis you hope to disprove, the one that usually proposes that no real difference exists, that any apparent patterns in your data are simply due to random sampling error, is called the ______ hypothesis.
null
In the previous question: "You are going to sample from a population that is normally distributed with μ=65 and a σ=9, if you sample six scores from the population what is the probability that the sample mean will be at least 4 below the population mean, in other words, p(M≤61)=?" What type of probability is that?
one-tail p value
Which of the following is correct? Note I made this worth 5 points just because it is so important.
p is the probability that we would have obtained that big of a difference between the sample means if H0 were true.
The probability of event 'A' occurring is symbolized as _______
p(A)
Which of the following best describes the relationship between p(A|B) and p(B|A)?
p(A|B) doesn't necessarily equal p(B|A) for they are two different things.
Review: In which of the following experiments would you reject H0?
p=0.05 p=0.02 p<.05 p<.001
The sampling distribution of the mean is itself a:
population
The null and alternative hypotheses are always about:
populations
When running an experiment what we want to know about are...
populations
If H0 is false, what is the probability that your data will lead you to correctly decide to reject H0?
power
A researcher wants to know what leads to better physical conditioning, downhill skiing or cross-country skiing. She obtains 30 volunteers who do not know how to ski, they are then allowed to select whether they would like to learn how to downhill ski or cross country ski. One group is taught how to downhill ski and subsequently go skiing 20 times during the winter, the other group is taught how to cross-country ski and they go skiing 20 times during the winter. At the end of the winter the physical conditioning of each student is measured. What type of experimental design is this?
quasi-experimental design
In null hypothesis testing you start by determining the probability of having obtained your data if the null hypothesis were true. If that probability is quite low then you decide to _________ the null hypothesis.
reject
