The mean score on a political attitude scale is 5 and the SD=2. The distribution is normal. Using the percentage approximations for the normal curve , how many people would a get a score between 5 and 9?
Use normal curve table
On a normal curve, what percentage of scores fall between a zscore of 1.29 and score of 1.49
use normal curve table % mean to Z = 40.15
Look up 1.49 =43.19.
A person has a score that is in the bottom 42% of the scores. What is the highest z score this person could have?(assume a normal distribution)
42-50=8%, , C-.20
If a person has an IQ of 130, approximately what percentage of people have higher IQ's? Assume M=100 SD=16
Look in z table. 3%
In a single throw of die, the probability of attaining a number 4 or lower is
you wish to survey the interests of students in your statistics class. You enter the names of all students into an excel spreadsheet. You then use a computer program to generate a list of random names. this is called
What if for problem 6 instead of the excel spreadsheet for the survey you simply wait at the door to the class and as people enter, you quickly survey them?
Haphazard selection, convinece sampling
The length of conversations between supervisors and workers in a particular manufacturing industry is normally distributed with a mean of 4.0 min and sd 0f 0.8 minutes. Use the normal curve table to answer the following:
What percentage of conversations are longer then 4.4 minutes? Convert to z.
longer then 5 minutes: 5-4/.8=1/.8=1.25=10.56%
longer then 3 mins: 3-4/.8=-1.25=39.44%
shorter then 2.5: 2.5-4/.8=1.875 In tail=3.01%
Which represents the situation in which the null hypothesis is true
place the 5 steps of hypothesis in order
A researcher tests whether there is any difference between how fast people work in the morning vs. how fast they work in the evening.
A.what is the null? there is no difference between peoples work speed in the morning vs evening
B.What is one possible research hypothesis? There is a difference
C.What is a second possible research hypothesis? pop 1 is significantly different from pop 2
suppose that the cutoff score on the comparison distribution is +- 2.31 you could reject the null if the sample values z score on this distribution was
A researcher wants to know if a new type of exercise program improves peoples health. Would this be a one tailed or two tailed test? WHY?
one tailed test because the study is only interested in whether the excersize increases the health
Failing to reject the null hypothesis when the research hypothesis is true is a *blank* error and incorrectly rejecting the null hypothesis is know as a
to reject the null hypothesis when the research hypothesis is true is a *blank* error and
type 2, type 1
A researcher is interested in whether the color of an animals surroundingf affects learning rate. She tests 16 rats in a box with colorful wallpaper. assume that it is known that the average rat can earn to run this particular maze (in a box without any s
What is the null hypothesis
The rats will not be able to run better with colorful surroundings
what is the standard of the distribution of means
square root of (64/16)=2.00
what is the shape of the distribution of means
suppose the sample means score on the comparison distribution is more extreme than the cutoff. What would the researcher conclude regarding the colorful wallpaper
in order to calculate the standardized effect one should divide the raw score effect size for each study by its
respective population standard deviation
having a very small of overlap between the distrubtion of pop 2 and the predicted distribution of pop 1
increases the power