Lying #1
Hypothesis Testing
z-statistic
Vocabulary
Other
100
What is a possible problem with a poll conducted online?
The poll could be biased based on the sample. Only certain people use the internet, and only certain people answer online polls. So, the poll wouldn't be targeting everyone and using methods to obtain an unbiased sample.
100
How do we find support for our hypotheses?
Try to disprove the null hypothesis because it is more efficient to rule out a hypothesis than to continuously seek supporting evidence.
100
What is the formula for the z-statistic and the sample error of the mean?
z=(m-M)/SEᴹ SEM=Ơ/√n
100
What is the null hypothesis? The alternative hypothesis?
Null: H0 nothing happened Alternative: HA something happened
100
You are looking to see if there is a significant different between the weights of black bears in NH and black bears in general. M=250, Ơ=50. The weights you recorded are: 241, 273, 502, 363, 431, 203, 288, 327. What is the value of n?
n=8
200
What is an unbiased sample?
An accurate representation of the entire population
200
What were Karl Popper's ideas about hypotheses?
They must be falsifiable because a hypothesis is a question you can test so there must be two possibilities for the solution.
200
Critical z-value for one and two tailed tests?
One tailed : -1.645 or 1.645 Two tailed: -1.96 or 1.96
200
What is a false alarm? A miss?
False alarm: Type I error, an overreaction Miss: Type II error, underreaction
200
You are looking to see if there is a significant different between the weights of black bears in NH and black bears in general. M=250, Ơ=50. The weights you recorded are: 241, 273, 502, 363, 431, 203, 288, 327. What is the sample mean?
m=328.5
300
What is the ideal way to conduct any type of poll?
unbiased sample unbiased questions
300
What is the p-value?
The probability that your effect is due to chance alone.
300
In absolute values, if your z-score is ___ that the critical value you ____ the null.
greater reject
300
What is a non-directional test? A directional test?
Non-directional: Predicts an effect but does not specify its direction Directional: Specifies the direction of the particular effect
300
You are looking to see if there is a significant different between the weights of black bears in NH and black bears in general. M=250, Ơ=50. The weights you recorded are: 241, 273, 502, 363, 431, 203, 288, 327. Should you perform a one-tailed z-test or a two-tailed z-test? What is your critical value?
You should perform a two-tailed z-test; the critical value is 1.96 or -1.96
400
What procedures does Gallup take when conducting polls in order to avoid a biased sample?
- They randomly select their participants - They keep calling until someone answers the phone - When calling a household, they ask for a specific selected person rather than just interviewing the person who answered the phone
400
What is the cutoff of the p-value to accept/reject the null?
If p > .05 accept null If p < .05 reject null
400
What are some assumptions of the z-test?
Random sampling from a defined population Interval or ratio scale of measurement Population is normally distributed
400
Why would you choose a one-tailed test or a two-tailed test?
One-tailed: You have a directional hypothesis Two-tailed: You have a nondirectional hypothesis
400
You are looking to see if there is a significant different between the weights of black bears in NH and black bears in general. M=250, Ơ=50. The weights you recorded are: 241, 273, 502, 363, 431, 203, 288, 327. What is the value of SEᴹ?
SEᴹ=17.67
500
You see the results of a poll that says "Majority of Americans want Ted Cruz to be the next president." You look into how the poll was conducted and see that 1,000 male participants were interviewed over the phone after being randomly selected from Texas phone books. What might have caused this poll to be biased?
- Only people living in Texas were interviewed - Only men were interviewed - The numbers were taken from the phone book rather than from lists of all phone numbers in use, and the people who actually have their phone numbers listed in phone books might possess inherent differences from the rest of the population
500
When you are testing hypotheses, should you attempt to prove a hypothesis or disprove a hypothesis? Which one should you prove/disprove?
You should try to disprove the null hypothesis
500
You recently conducted a study to determine if Psychology students have higher IQs than students in general. You tested 27 Psychology students and got an average IQ score of 105. The population mean is 100 with a standard deviation of 15. What is your z-statistic? Should you reject or accept the null?
z=1.74; reject the null hypothesis
500
How do a "z-score" and a "z-statistic" or "z-test" differ from each other?
A z-score measures the distance between an individual score and the mean. A z-statistic or z-test measures the distance between a sample mean and the population mean.
500
You are looking to see if there is a significant different between the weights of black bears in NH and black bears in general. M=250, Ơ=50. The weights you recorded are: 241, 273, 502, 363, 431, 203, 288, 327. What is the calculated z-statistic? Should you reject or accept the null hypothesis?
z=4.44; reject the null
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