PSY 350 M2 Tutorial Quiz

A person has a score that is in the bottom 42% of the scores. What is the highest Z score this person could have?

-.20

A person received a test score that is in the top 32% and the test scores follow a normal curve. The person's Z score must be at least:

.46

Jake's Z score for running ability is .60. What is Jake's raw score? (assuming M=100 and SD=7)

104.2

Suppose the cutoff Z score on the comparison distribution is +-2.31. You could reject the null hypothesis if the sample value's Z score on this distribution was:

2.83

You randomly select someone from a group of 12. Two of those in the group were born in Iowa. What is the chance you will pick a person born in Iowa?

2/12=.17

If a person has an IQ of 130, approximately what percentage of people have higher IQs? Assume M=100 and SD=16

3%

John attained a score of 65 on his stats exam. The mean for the class was a 70 with a SD of 10. What is the percentage of students scored below and above John?

31 and 69

If you were to select a score at random from a distribution that follows a normal curve, what approximately is the probability of selecting a score between Z scores of 0 and +1?

34%

Using the percentage approximations for the normal curve, what percentage of scores are between the mean and one standard deviation below the mean?

34%

The mean score on a creativity test is 20 and the standard deviation is 5. The distribution is normal. Using the percentage approximations for the normal curve, how many people would attain a score between 15 and 25?

34%+34%=68%

What Z score would a person need to be in the top 4% of his or her class on a particular test? Assume a normal distribution.

50%-4%=46%; which corresponds to a Z score of 1.75

A particular nation has a human rights score of 41, which equals a Z score of 1.3. What is the percentage of nations above this score?

9.68%

Failing to reject the null hypothesis when the research hypothesis is true is referred to as:

?

In a housing project there are 350 households in which English is usually spoken, 50 in which Spanish is usually spoken, and 100 in which the language is other than English or Spanish. A researcher approaches a house at random to conduct an interview. What is the chance that the usual language in that household will NOT be English?

?

A researcher conducts extensive interviews with 40 workers at a large factory in other to examine the morale among workers in general at that factory. In this example, what is the population?

All the workers in the factory

Another name for research hypothesis is the:

Alternative Hypothesis

You determine the characteristics of the comparison distribution to answer which of the following questions?

Given a particular sample value, what is the probability of obtaining that value if the null hypothesis is true?

The results of a study are not extreme enough to reject the null hypothesis. What can the researcher conclude with reasonable confidence?

None of the above; the results are inconclusive

For the following question: A researcher is interested in a new kind of exercise. This is new exercise can be done by anyone because it does not require any equipment, and therefore could be potentially beneficial without cost to the person. The researcher is interested in whether this new exercise will reduce the rate of heart attacks in the people who participate in doing it. What is the research hypothesis?

The exercise will reduce the rate of heart attacks

Suppose you conduct a study in which you set the significance level cutoff at a lenient probability level, such as 15%. In this case, you would have a 15% chance of making a:

Type I error

If you were looking at a graph of a normal distribution, which of the following would best describe it?

Unimodel, roughly symmetrical, and bell-shaped

Suppose that a researcher wants to know if a new flu drug effects people, either by making them better or worse. Would this be a one-tailed or two-tailed test and why?

WRONG Two-tails because there are two variables - whether or not people take the drug and how their flu is affected

Setting the significance level cutoff at .10 instead of the more usual .05 increases the likelihood of:

a Type I error

The fact that probabilities are proportions means that they:

can't be lower than zero or more than one

The ____________ explains why many distributions tend to be close to normal in the real world.

central limit theorem

There is a special complication when using at two-tailed test. The researcher must:

divide up the significance percentage between the two tails of the distribution

If you want to know something about a population, your results would be MOST accurate if you could study the:

entire population

A researcher is interested in the effect of going through a terrorist attack on the attitude of police officers about the goodness of people in New York City. After the attack, police may hold more positive about people (because of various acts of heroism and altruism exhibited exhibited by residents) or more negative outcomes (looting and dishonesty after the event.) What type of hypothesis should the researcher make?

nondirectional

Based on the result of his study, a researcher rejects the null hypothesis because the probability of obtaining his result if the null hypothesis were true is less than 5%. How would this be symbolized?

p<.05

The actual values of the mean, variance, and standard deviation of a population are called:

population parameters

A result is considered statistically significant when a sample value is so extreme that:

the null hypothesis is rejected

A sample is studied to see if it represents a population (called Population 1) that is different from a known population (called Population 2). The comparison distribution is:

the same as the distribution of Population 2

A researcher tests whether there is any difference between how fast people work in the morning versus how fast they work in the evening. What is the NULL hypothesis?

there is no difference in the speed at which people work

You want to know if a new employee incentive program really works. How would you test the hypothesis that it does work?

try to disprove the hypothesis that it does not work