Sampling & Probability
Ch. 5.4
A Type II error occurs whenever a(n): _________ null hypothesis is not rejected.
Incorrect
Ch. 6.2
In a normal distribution, _____% of the scores fall below the mean.
50%
Ch. 6.2
The process of converting individual raw scores in a normal distribution to a set of scores for which the percentiles are already known is called:
Standardization
Ch. 7.2
If you reject the null hypothesis, the result is said to be:
Statistically significant
Ch. 5.1
The two types of errors possible in hypothesis testing are:
Type I and Type II
Ch. 5.1
The use of random assignment indicates that the researcher is conducting which type of study?
an experiment
Ch. 6.1
What will happen to a distribution of scores in a sample if the number of scores increases?
The distribution of scores in a sample will approach normality (become more normal)
Ch. 6.2
To what percentile does a z score of −1.0 roughly correspond?
16th percentile
Ch. 7.1
To convert a person's percentile rank into a raw score, you need to know the mean and the ________ of the population,
Standard deviation
Ch. 5.4
If a researcher fails to reject the null hypothesis when the null hypothesis is in fact false, what error have they made?
Type II error
Ch. 5.2
When a person pays attention to evidence that confirms what they already believe and ignores evidence that would disconfirm their beliefs, they are demonstrating _____ bias.
Confirmation
Ch. 6.1
The normal curve has three defining characteristics. These are:
1. Unimodal
2. Symmetric
3. Defined Mathematically
Ch. 6.2
A z-score of -2.0 would indicate scores that were at or about the:
2nd percentile
Ch. 7.3
The symbol for the null hypothesis is _____, and the symbol for the research hypothesis is _____.
Null: H0
Research: H1
Ch. 6.3
The population of all standardized exam scores has a mean of 500 and a standard deviation of 100. Twenty-five students in a professor's class take the exam, and their average score is 525.
What is the z statistic that is associated with the class's average?
+1.25
Ch. 5.3
In a study designed to investigate the link between sugar and hyperactivity, a researcher assigns one group of children to eat a high-sugar snack and another group of children to eat a snack with no sugar. The control group in this experiment was the:
group of children assigned to eat a no sugar snack.
Ch. 6.1
When a distribution has exactly 50% of scores that fall below the mean and 50% that fall above the mean, it is considered________.
Symmetrical
Ch. 6.2
It is known that the mean weight of the population of newborn infants is 7.5 pounds, with a standard deviation of 1.1 pounds. What is the weight (in pounds) of a newborn infant with a z score of +0.5?
8.05 pounds
Ch. 7.2
A group of researchers is interested in whether dogs find a hidden treat better when the location is marked with an object or pointed to by a human. Dogs are given 10 tries using an object marker and 10 tries with a human pointer. The average number of treats found in each group is compared.
Please state the null hypothesis for this study.
There will be no difference between the number of treats found by dogs in the object-marking group than in the pointing group.
Ch. 5.2
You flip a coin 50 times, and the proportion of heads is 0.60. How many times did the coin land on heads?
30 times
Ch. 5.4
A counselor tests a new therapy with their clients. At the end of six months, they find that the therapy significantly lowered anxiety symptoms. In other words, they rejected the null hypothesis. If the null hypothesis is actually true, the counselor has made what error?
Type I error
Ch. 6.2 (need calculator)
The mean SAT score for seniors who took the test in 2022 was 1050. If the standard deviation for this same year was 209, what is the raw score for a person with a z score of +1.50?
1363.5
Ch. 6.3
What is the standard error for a distribution of sample means with a population standard deviation of 15 and a sample size of 36?
2.50
Ch. 7.1
What is the percentage of observations that fall between a z score of −1.20 and +0.50?
57.64%
Ch. 7.1
If σM = 5 and N = 100, then σ =
50