PSYCH STATS CH 1-5 Homework questions
Name and describe circumstances where the median would provide a better measure of central tendency than the mean?
1. Extreme scores 2. Undetermined values 3. Open ended questions or category
What are two characteristics of the mean that have to do with deviation scores?
1. The sum of the deviation scores is zero 2. The sum of the deviation scores is squared is a minimum.
After five points are added to every score in a distribution, the mean is calculated and found to be μ = 30. What was the value of the mean for the original distribution.
25
What additional information is obtained by measuring on an ordinal scale compared to a nominal scale? a. whether the measurements are the same or different b. the direction of the differences c. the size of the differences
B.
Statistical techniques are classified into two major categories: Descriptive and Inferential. Describe the general purpose of each category
Descriptive: Set of procedures that produce a single number or figure to summarize an entire set of data. inferential: Represents statistical techniques that allow researchers to use measurements from samples
What are the basic characteristics of an experiment that differentiate this method from other types of research?
Experiment determines cause and effect "True experiment" One variable is manipulated and one is measured Independent variable is being manipulated and dependent is being assessed. The researcher has high control
Describe the concept of sampling error
Naturally occurring discrepency or error that exists between a sample statistic and the corresponding population parameter.
Out of the four scales of measurement was would you describe social security numbers?
Nominal Scale
Out of the four scales of measurement was would you describe Birth order?
Ordinal Scale
Out of the four scales of measurement was would you describe the state legislators car license numbers which are issued in order of seniority.
Ordinal scale
Out of the four scales of measurement was would you describe Wind speed?
Ratio scale
What is the purpose for obtaining measure of central tendency?
to determine the single score that defines the center of a distribution
For a positively skewed distribution with μ = 30, the median would have a value: a. less than 30 b. equal to 30 c. greater than 30
A.
One item on a questionnaire asks, "How many siblings did you have when you were a child?" A researcher computes the mean, median, and mode for a set of n=50 responses to this question. Which of the following statements accurately describes the measures of central tendency? a. Because the scores are all whole numbers, the mode will be a whole number b. because the scores are all whole numbers, the median will be a whole number c. because the scores are all whole numbers, the mean will be a whole number
A.
The average SAT score for the entire class if entering freshmen is 530. However, if you select a sample of 20 freshmen and compute the average verbal SAT score you probably will not get exactly 530. What statistical concept is used to explain the natural difference that exists between a sample mean and the corresponding population mean. a. sampling error b. inferential error c. statistical error
A.
The relationship between a statistic and a sample is the same as the relationship between a. parameter and statistic b. statistic and parameter c. a sample and population
A.
A recent study reports that infant rats are fed a special protein enriched diet an adult weight 10% greater than litter mates raised on regular diet. For this study, what is the independent variable? a. the rats given protein b. rats given regular diet c. the type of diet given to rats
C.
A researcher wants to examine the relationship between sleeping habits and grade point average for college students. A group of 100 students is selected and each student is asked to report the average number of hours he/she sleeps at night and his/her GPA. What research method is being used in this study? a. experimental method b. non-experimental method comparing two groups c. correlational method
C.
A teacher gave a reading test to a class of 5th grade students and computed the mean, median, and mode for the test scores. Which of the following statements cannot be an accurate description of the scores. a. no one had a score equal to the mean b. no one had a score equal to the median c. no one had a score exactly equal to the mode
C.
For a negatively skewed distribution with a mode of X=25 and a mean of M=20, the median is probably ________ a. greater than 25 b. less than 20 c. between 20 and 25
C.
How would the following in mathematical operation be expressed in summation notation? "Subtract 4 points from each score, square the resulting value, then find the sum of the squared numbers" a. EX-42 b. (EX-4)2 c. E(X-4)2
C.
A researcher is interested in the sleeping habits of American college students. A group of 50 students is interviewed and the researcher finds that these students sleep an average of 6.7 hours per day. For this study, the 50 students are a example of? a. population b. statistic c. parameter d. sample
D.
The value of one score in a distribution is changed from X=20 to X=30. Which measure(s) of central tendency is (are) certain to be changed?
The mean
A researcher is measuring problem solving times for a sample of n=20 children. However, one of the children fails to solve the problem so the researcher has an undetermined score. What is the best measure of central tendency for this data?
The median
For the following scores, identify which measure would provide the best description of central tendency and explain your answer 0, 40, 41, 43, 43, 44, 45, 47, 48
The median because 0 is an outlier and it skews the distribution and fluctuates the mean
Out of the four scales of measurement was would you describe probability statements about rain
interval scale
