Statistics test 3
In a distribution of scores having a mean of 75 and a standard deviation of 6.38, what percent of scores fall above a raw score of 80?
21.77%
The mean of a normally distributed population is 225. What is the mode?
225.0
If u=40 with a o=8.5, based on the curve, what is the value of x at the point on the distribution labeled -2.0.
23.0
In a distribution of scores having a mean of 75 and a standard deviation of 6.38, what percent of scores fall between raw scores of 70 and 80?
56.46%
What is the raw score that corresponds to a z-score of -1.15 when u=75 and o=15?
57.75
Your z-score is -1.6. What is the raw score?
58.16
In a distribution of scores having a mean of 75 and a standard deviation of 6.38, what percent of scores fall between raw scores of 81 and 83?
6.8%
In a normal distribution of data, your mean is 85 and your standard deviation is 2.5. Your z score is 1.2. What is the raw score?
88.0
Suppose that your sample of 50 registered voters has a mean age of 68 years and a standard deviation of 10 years. What would be your margin of error at the 95% confidence level?
+2.77 years
A 95% level of confidence means that 95 of every 100 samples taken would do which of the following?
- capture the mean from the population - capture the proportion from the population
In a normal distribution of data, your mean is 85 and your standard deviation is 2.5. Your raw score is 65. What is the z score?
-8.0
What proportion of the normal distribution is above a z-score of 1.34?
0.0901
Probability of score selection in area space between -1.0 and -2.0 standard deviation below the mean
0.1359
Probability of score selection in area space below the mean
0.5
In a normal distribution, the sum of the probabilities of all scores above the mean is equal to ________:
0.50
Probability of score selection in area space between -1.0 and +1.0 standard deviations around the mean
0.6826
The null hypothesis is considered as the ______ outcome.
no effect
T/F: A 90% confidence level can be interpreted to a mean that is 90% of residents of New York City has given between $10-20 to homeless people."
false
Where on the x-axis of a normal curve do the measures of central tendency occur?
in the middle (z0)
Most real-world research hypotheses are ______ in nature.
non directional
A research hypothesis that makes a prediction of a lower score on a measure of the DV would require a ___________
left-tailed test
The pattern of data that is symmetric around a midpoint and fairly accurately predicts reality is called a...
normal curve
Given the statement, sample 1 is expected to score higher than sample 2, what is the correct null hypothesis?
H0= 1<2
What is the difference between an experimental and non-experimental study?
In an experiment study the IV is actively manipulated while in a non-experiment study the IV is not actively manipulated
T/F: In a distribution with a mean of 150 and a standard deviation of 20, a z-score of -2.0 would convert into a raw score of 110.
true
T/F: Since experimental conclusions are based on probibility, no hypothesis test results in 100% certainty.
true
T/F: The probability of a type 2 error is represented as beta (B).
true
T/F: The type 1 error rate is always .05 or .01
true
The p-value of an outcome is the probability of obtaining a result at least as extreme as the one observed if the null hypothesis is ......
true
A ______ represents the number of standard deviations a particular score is from the mean.
z-score
What is the formula (x-u)/o used to calculate?
z-score
If we wished to compare two scores that are measured on different scales, we would need to transform the scores into ______.
z-scores
A "sure thing" would have a probability equal to:
1.0
Your raw score is 85.0. What is the z-score?
1.09
The mean of a population of IQ scores is 100. What is the mean of the distribution of sample means for samples of size 64?
100.0
The mean of a population of IQ scores is 100. What is the mean of the distribution of the sample means for samples of size 100.
100.0
What is the raw IQ value that corresponds to a z-score of -0.87, when μ= 256.3 and σ= 23.4?
235.94
The median of a normally distributed population is 28. What is the mean?
28.0
99% Cl if mean =30.25 (s=2.83, n=20) when o=3.40 and N=250
28.29 < u < 32.21
95% Cl if mean =30.25 (s=2.83, n=20) when o=3.40 and N=250
28.76 < u < 31.74
In a distribution of scores having a mean of 75 and a standard deviation of 6.38, what percent of scores fall below a raw score of 63?
3.01%
If u=40 with a o=8.5, based on the curve, what is the value of x at the point on the distribution labeled +1.0.
48.5
In a normal distribution with a mean of 100 and a standard deviation of 16, what score below is within one standard deviation from the mean?
90
The lowest level of confidence that is conventionally used with large samples is _______%
90
The highest level of confidence that is conventionally used with large samples is ______%
99.0
Why is z score a standard score?
Because it has been converted into scores that fit on the normal curve.
Why can different distributions be compared to one another once they are converted into standard scores?
Because they all fit on the same curve now
Two distributions, A and B, have the same mean, but Distribution A has o=4 and Distribution B has o=1.0. Which distribution has the greatest spread?
Distribution A has the greatest spread
The mean of a normally distributed population is 75 with a standard deviation of 8. If someone has a z-score of 2, what does this mean?
S/he is two standard deviations above what is average, or the mean
What areas on the graph makes up the lowest 15.8% of the distribution?
The points on the far left ( 60-80 )
In order to compare an individual score to a distribution, we need to convert what?
The raw score into a standard score
Two students from two different schools recently took a science test. The first student correctly answered 34 questions on the test and the second student correctly answered 48 questions. What can you conclude from the two students' test scores?
The two students cannot be compared bc there was no standardization procedure permitting appropriate comparisons.
The null hypothesis is stated so as to be ______ to the alternative hypothesis.
complementary
Most distributions in nature tend to be _________ distributed.
normally
Level of confidence refers to the probability that our interval estimate will contain the...
parameter
Along with whether a result has statistical significance, a researcher should also be concerned with whether the result has ________ significance.
practical
The core logic of hypothesis testing is built around the concept of:
proof by contradiction
Another name for sampling error is _______error.
random
t= 1.27 , p < .05
reject the null
z= 9.32, p= .002
reject the null
Probability is key to assessing:
risk
Which a two-tailed test, the rejection region is___________
split between the two tails of the distribution
Cohen's d is used to calculate a ______ effect size.
standardized
A two-tailes test is appropiate for a hypothesis that does not predict "more ______" or "less ________" outcome.
than, than
Which of the following determines alpha?
the size of the rejection region
