Natalia Exam 2 Stats

What is sampling error and why should we care?

-amount of error between a sample statistic and population parameter -we should care because it is always a problem and it is why we do statistics

What is the difference between standard deviation and standard error:

Standard Deviation= average distance between the score and the mean Standard Error= average distance of a sample mean from a population mean

When a random sample is selected from a population, the sample mean is not expected to be exactly equal to the population mean. On average, the size of the difference between a sample mean and the population mean is predicted by:

The standard error

You complete a hypothesis test using alpha= .05 and based on the evidence from the sample, your decision is to reject the null hypothesis. If the treatment actually has no effect, which of the following is true? a. You have made a type 1 error b. You have made a type 2 error c. You have made a no error d. Cannot be determined

a. You have made a type 1 error

Define probability: a. likelihood b. certainty c. subjective d. is just a term for luck

a. likelihood

What is the probability of randomly selecting a z-score greater than z= -0.80 from a normal distribution? a. .2118 b. .7881 c. .80 d. 80%

b. .7881

How large does the sample size need to be normal: a. 10 b. 30 c. 100 d. 1000

b. 30

A teacher gave a reading test to a class of 5th grade students and computes 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 exactly equal to the mean b. No one had a score exactly equal to the mode c. No one had a score exactly equal to the media d. Cannot be determined

b. No one had a score exactly equal to the mode

A recent study reports that infant rats fed a special protein-enriched diet reached an adult-weight 10% greater than litter-mates raised on a regular diet. For this study, what is the independent variable? a. infant rats b. diet c, age d. weight

b. diet

One group of new freshmen is given a study-skills training course during the first week of college and a second group does not receive the course. At the end of the semester, the grade point average is recorded for each student. For this study, what is the dependent variable? a. study-skills training b. grade point average c. freshman who did not receive training d. freshman who did receive training

b. grade point average

The symbol that corresponds to the standard error of M is: a. μ b. σxˉ​​ (sigma sub x-bar) c. 𝜎 d. e

b. sigma x-bar (𝞼, x bar)

A z-score of z = -2.00 indicates a position in a distribution:

below the mean by a distance equal to 2 std. dev.

As the sample size increases, the standard error of M: a. increases b. stays the same c. decreases d. depends on size of increase

c. decreases

Probability values are always: a. greater than or equal to 0 b. less than or equal to 1 c. positive numbers d. All of the above

d. All of the above

Psychology is defined as the scientific study of: a. people and things b. emotions and beliefs c. perception and religion d. mind and behavior

d. mind and behavior

The distribution of sample means (for a specific sample size) consists of _______.

the sample means for all the possible samples (for the specific sample size)

If an entire population with pop. mean= 60 and pop. standard deviation= 8 is transformed into z-scores, then the distribution of z-scores will have a mean of ______ and a standard deviation of _______.

μ = 0 ; 𝜎 = 1