stats midterm
true experiment
From which of the following studies can one most reasonably determine cause and effect?
the standard deviation will be unchanged
If 10 points were added to each score in a distribution, which of the following will happen?
both mutually exclusive and exhaustive
If P + Q = 1.00 then P and Q must be _________.
perfect
If Syx= 0.0 the relationship between the variables is _________.
-0.80
If X and Y are transformed into z scores, and the slope of the regression line of the z scores is −0.80, what is the value of the correlation coefficient?
negatively skewed
If a distribution of raw scores is negatively skewed, transforming the raw scores into z scores will result in a _________ distribution.
56.76 and 33.24
If a population of scores is normally distributed, has a mean of 45 and a standard deviation of 6, the most extreme 5% of the scores lie beyond the score(s) of _________.
0.6000
If a stranger gives you a coin and you toss it 1,000,000 times and it lands on heads 600,000 times, what is p(Heads) for that coin?
p(A)p(B)
If events A and B are independent, then p(A and B) = _________.
mutually exclusive
If p(A or B) = p(A) + p(B) then A and B must be _________.
independent
If p(A)p(B|A) = p(A)p(B), then A and B must be _________.
0.302
If r = 0.4582, sY = 3.4383, and sX = 5.2165, the value of bY = _________.
0.60
If sY = sX = 1 and the value of bY = 0.6, what will the value of r be?
Y (with line on top)
If the correlation between two sets of scores is 0 and one had to predict the value of Y for any given value of X, the best prediction of Y would be _________.
mean
If the distribution is symmetrical, which is the best measure of central tendency?
biased
If the probability of drawing a member of a population is not equal for all members, then the sample is said to be _________.
as X increases, Y decreases
In a negative relationship, _________.
54
In a particular relationship N = 80. How many points would you expect on the average to find within ±1 Syx of the regression line?
scientific method
In acquiring knowledge the method that employs logic, reasoning and objective assessment is referred to as _______.
also uses methods of descriptive statistics and allows one to make inferences about a population based on sample data
Inferential statistics _________.
independent variable
Let's assume you are conducting an experiment to determine the effect of a new drug on the incidence of epileptic seizures. You select 20 epileptics from the 150 epileptics being treated at a nearby hospital and administer the drug to them. You record the number of seizures in each of the 20 subjects for one month. The new drug is an example of a(n) _________.
0.9250
Let's assume you are having a party and have stocked your refrigerator with beverages. You have 12 bottles of Coors beer, 24 bottles of Rainier beer, 24 bottles of Schlitz light beer, 12 bottles of Hamms beer, 2 bottles of Heineken dark beer and 6 bottles of Pepsi soda. You go to the refrigerator to get beverages for your friends. In answering the following question assume you are randomly sampling without replacement. What is the probability the first beverage you get is a beer?
inferential statistics
Mathematical methods used to draw tentative conclusions about a population based on sample data are referred to as _________.
discrete
Number of bar presses is an example of a(n) _______ variable.
11.70
On a test with a population mean of 75 and standard deviation equal to 16, if the scores are normally distributed, what is the percentile rank of a score of 56?
ratio
Reaction time in seconds is an example of a(n) _________ scale.
false
true or false: Naturalistic observation is rarely used by scientists because it does not make use of the scientific method.
false
true or false: Observational studies involve the manipulation of variables by the investigator.
true
true or false: Of the measures of central tendency, the mean is the least subject to sampling variations.
true
true or false: The higher the r value, the lower the standard error of estimate.
false
true or false: The independent variable is the variable that is measured to determine the effect of the independent variable.
true
true or false: The main difference between rationalism and the scientific method is that the scientific method relies on objective assessment to test the idea.
false
true or false: The mean is most subject to sampling variation.
true
true or false: The measurements that are made on the subjects of an experiment are called data.
true
true or false: The median and the 50th percentile rank score will always have the same value.
true
true or false: The method of authority is opposed to the scientific method.
false
true or false: The only value of random sampling is to achieve a representative sample.
false
true or false: The real limits of a discrete variable are those values that are above and below the recorded value by one half of the smallest measuring unit of the scale.
false
true or false: The relationship between the two variables must be nonlinear.
true
true or false: With grouped scores, the mode is the mid-point of the interval with the highest frequency.
false
true or false: With the exception of division, one can perform all mathematical operations on a ratio scale.
true
true or false: z scores allow comparison of variables that are measured on different scales.
false
true or false: Σ X^2 and (Σ X)^2 generally yield the same answer.
rho, phi, pearson r, eta
what are some correlation coefficients?
nominal scale
"Brand of soft drink" is measured on a(n) _________.
0.231
A "hungry" undergraduate student was looking for a way of making some extra money. The student turned to a life of vice - gambling. To be a good gambler, he needed to know the probability of certain events. Help him out by answering the following question. The probability of drawing a face card (king, queen or jack) of any suit from a deck of 52 ordinary playing cards in one draw is _________.
0.8041
A certain university maintains a colony of male mice for research purposes. The ages of the mice are normally distributed with a mean of 60 days and a standard deviation of 5.2. Assume you randomly sample one mouse from the colony. The probability his age will be between 55 and 70 days is _________.
never provides exact measurements and can take an infinite number of intermediate possible values
A continuous scale of measurement is different than a discrete scale in that a continuous scale _________.
60.0
A distribution has a mean of 60.0 and a standard deviation of 4.3. The raw score corresponding to a z score of 0.00 is _________.
53.5
A distribution has a mean of 60.0 and a standard deviation of 4.3. The raw score corresponding to a z score of −1.51 is _________.
may be anywhere in the range 0.345-0.355 grams
A nutritionist uses a scale that measures weight to the nearest 0.01 grams. A slice of cheese weighs 0.35 grams on the scale. The true weight of the cheese _________.
a probability value determined after collecting data
A posteriori probability refers to _________.
a probability value deduced from reason alone
A priori probability refers to _________.
imperfect, nonexistant, perfect
A relationship can be _________.
the set includes all of the possible events
A set of events is exhaustive if _________.
53.66
After performing several clever calculations on your calculator, the display shows the answer 53.655001. What is the appropriate value rounded to two decimal places?
0.5556
Assume you are rolling two fair dice once. The probability of obtaining at least one 3 or one 4 equals _________.
median
Consider the following scores: 21, 22, 22, 0.1, 20, 25, 28, 26, 23, 19, 0.5. Which of the measures listed below would give the best description of the central tendency of these scores?
correlation is primarily concerned with the size and direction of relationships, and regression is primarily used for prediction
Correlation and regression differ in that _________.
calculate the mean and standard deviation of a sample, calculate the mean and standard deviation of a population, and graph a distribution of raw scores
Descriptive statistics are used to _________.
Σ (Y − Y')2
The least-squares regression line minimizes _________.
d. 0.15
The lowest degree of correlation shown below is _________. a. −0.25 b. 0.75 c. −0.33 d. 0.15
to determine if the relationship is linear or curvilinear
The primary reason we use a scatter plot in linear regression is _________.
0.50
The proportion of scores less than z = 0.00 is _________.
r2
The proportion of variance accounted for by a correlation between two variables is determined by _________.
Σ (Y − Y')2
The regression equation most often used in psychology minimizes _________.
1
The standard deviation of the z distribution equals _________.
independent variable
The variable that the experimenter manipulates is called the _________.
impossible to compute from the information given
The z score corresponding to a raw score of 120 is _________.
0
The z score corresponding to the mean of a raw score distribution equals _________.
random
To avoid unknown, systematic factors that may bias the results of an experiment, the experimenter should select a _________ sample from a population and use controlled conditions
the occurrence of one has no effect on the probability of occurrence of the other
Two events are independent if _________.
they both cannot occur together
Two events are mutually exclusive if _________.
6.05-6.15
What are the real limits of the observation of 6.1 seconds (measured to the nearest second)?
Y (with line on top)
What would you predict for the value of Y for the point where the value of X (with line on top) is ?
lower the correlation
When a correlation exists, lowering the range of either of the variables will _________.
whether the relationship is linear or nonlinear, and type of scale of measurement for each variable
When deciding which measure of correlation to employ with a specific set of data, you should consider _________.
statistic
When one analyzes data based on a sample, one calculates a _________.
Method of Authority
Which method of knowing is used in the following example? An individual accepts as true that black holes exist because 10 physics Nobel laureates assert such is the case.
the relationship should be linear, and predictions for Y should be within the range of the X variable in the sample
Which of the following statement(s) is (are) an important consideration(s) in applying linear regression techniques?
must be greater than 0.00 and have a percentile rank greater than 50%.
You have just received your psychology exam grade and you did better than the mean of the exam scores. If so, the z transformed value of your grade must
the career requiring good writing skills.
You have just taken a standardized skills test designed to help you make a career choice. Your math skills score was 63 and your writing skills score was 45. The standardized math distribution is normally distributed, with μ = 50, and σ = 8. The writing skills score distribution is also normally distributed, with μ = 30, and s = 10. Based on this information, as between pursuing a career that requires good math skills or one requiring good writing skills, you should chose _________.
true
true or false: A parameter is a number calculated on population data that quantifies a characteristic of the population.
true
true or false: A correlation coefficient expresses quantitatively the degree of relationship between two variables.
true
true or false: A fundamental property of a nominal scale is equivalence.
true
true or false: A sample is a subset of a population.
true
true or false: A statistic is a number calculated on sample data that quantifies a characteristic of the sample
true
true or false: Causation implies correlation.
true
true or false: In order to determine cause and effect, a researcher needs to do a true experiment.
true
true or false: Measurement is always approximate with a continuous variable.
false
true or false: Most scales used for measuring psychological variables are either ratio or interval.