PY 211 Unit 2 Questions

For each obtained value stated, what is the decision for each if a=.01 (two-tailed) a. z=2.10 b. z=1.70 c. z=2.75 d. z-3.30

a. .0179 reject b. .0446 reject c. .0030 retain d. .0005 retain

How are the rejection regions, the probability of a Type I error, the level of significance and the alpha level related?

they are all located in the tails

What is a Type I error (alpha)

when the null hypothesis is rejected when it should be retained

What are the values of the mean and standard deviation in a standard normal distribution?

Mean=0 Standard Deviation=1

Why is a normal distribution applied to behavioral research?

The researcher can see how people's emotions and behaviors can relate to those of other people. They can see if someone has a behavioral problem such as aggression or anxiety.

Distinguish between the significance and the effect size of a result

The significance determines the effect that the treatment had on the hypothesis

Define Normal Distribution

a distribution in which scores are symmetrically distributed above and below the mean, median and mode at the center of the distribution

What is a z score?

a numerical value on the x-axis of a standard normal distribution. Specifies the distance or number of standard deviations that a value is above or below the mean

Define the central limit theorem

it states that as the numbers increase, regardless of the scores in a population, the distribution of the sample mean will be shaped like a normal distribution

A researcher conducts a hypothesis test and concludes that his hypothesis is correct. Explain why this conclusion is never an appropriate decision in hypothesis testing.

nothing is proven definitely

What is a sampling distribution?

one in which all sample means or sample variances that could be obtained in samples of a given size from the same population

The inaccuracy of a lie detection. How does the researcher know that very few people will be highly accurate at lie detection?

she has done research using a standard normal distribution and z scores with people taking a lie detector test and the research revealed that only a few percentage of people tested way above the mean (in the tails of the distribution)

What is the power in hypothesis testing?

the likelihood of detecting an effect

The sample mean is an unbiased estimation of the population mean. Explain

the sample is taken from the population randomly. This means that the sample mean on average is equal to the population mean

Why is the following true: µ=µM

the sample mean is equal to the population mean on average because the sample mean is an unbiased estimator of the population mean

What is a Type II error (beta)

when the null hypothesis is retained when the null hypothesis is actually true

Visual sequential memory and poor spellers. Good readers/spellers 93.8+/-2.9 Bad spellers/readers 84.8+/-3.0 a. what % of participants correctly read at least 90 words in the good readers and good spellers group? b. what % of participants correctly read at least 90 words in the average readers and poor spellers group

a. .0951 b. .0418

The sample mean is an unbiased estimator of the population mean. What do we expect the sample mean to be equal to when the population mean is: a. 8 b. 0 c. 20 d. ∞ e. -∞ f. .03

a. 8 b. 0 c. 20 d. ∞ e. -∞ f. .03

Distinguish between sampling where order matters and sampling where order doesn't matter

a. In theory, order does matter b. In practice, order doesn't matter

State whether each of the following statements concerning the sample mean is true or false

a. the value of the sample mean equals the population mean on average: true b. the value of the sample mean can vary from sample to sample: true c. there is more than a 5% probability of selecting a sample mean that is farther than 2 SEM from the population mean: false d. the sampling distribution of sample means is approximately normally distributed: true

What are the critical values for a one-sample nondirectional (two-tailed) z test at a .05 level of significance?

+/-1.96

Distinguish between sampling with replacement and sampling without replacement

-w/replacement: data selected is returned to the group it was taken from before redrawing -w/out replacement: data selected is not replaced before redrawing

What are two steps to locate proportions under the normal curve?

1. change the raw score to a z score [x-M/SD] 2. look up the corresponding proportion for the z score in the unit normal table

State the 8 characteristics of the normal distribution

1. mathematically defined 2. theoretical 3. the mean, median and mode are in the 50th percentile 4. symmetrical 5. the mean can equal any value 6. standard deviation can equal any positive value 7. the area under the curve is equal to 1 8. the tails are asymptotic

What are two decisions that a researcher makes in hypothesis testing?

1. reject null hypothesis 2. retain null hypothesis

State the 4 steps of hypothesis testing

1. state hypothesis 2. set criterion 3. gather information 4. make decision