Psyc 210 E2 Review

There are various ways to express a single observation, and they are all referring to the same observation and the same location on the normal curve. These expressions can best be described as...

• percentile, z score, and standard score

• z score, percentile, and raw score

• unit, z score, standardized

• formal, standardized, and normal

A z score ____ to the mean will always be ____.

• equal to; zero

• equal to; positive

• below; positive

• above; negative

What percent of observations fall between z scores of -1.41 and 0.17?

Answer explanation

Explanation: using the z table, find the z score -1.41. The probability for z = -1.41 is appx .0793 (% in tail). Find the z score of 0.17. The probability for z = 0.17 is appx .5675 (50 - % mean to z). Take .5675 - .0793 = .4882 * 100 = 48.82%

In a statistics course, students reported studying an average of 7.59 hours per week, with a standard deviation of 3.42. Assuming this class is a population, what percent of students study more than 7 hours per week? (Round the z score to two decimal places.)

Answer explanation

Explanation: first, calculate z. z = (X - μ) / σ ; x = 7, μ = 7.59, σ = 3.42. z = (7 - 7.59) / 3.42 = -.17. Take 50 + 6.75 (% mean to z) = 56.75%

Nonparametric tests ____ based on assumptions about the population whereas parametric tests ____ based on assumptions about the population.

• are not; are

• are; are not

• are sometimes; are sometimes

Assuming the population distribution is appx normal is okay if...

• we are careful about generalizing

• we have a sample includes at least 30 scores

• if the data is not nominal or ordinal

• participants are randomly selected

Select all that apply when listing the assumption(s) of the hypothesis testing:

• if we have an effect size of .5 = it is assumed to be large

• population is distribution is appx normal = okay if the sample is at least 30

• participants are randomly selected = okay if we are careful about generalizing

• dependent variable is on a scale measure = usually okay if data are not clearly nominal or ordinal

The central limit theorem states that if sample sizes are at least __, the distribution will more than likely resemble a ____ distribution.

• 20; normal

• 30; normal

• 20; non normal

• 30; non normal

The research hypothesis states ____

• the results are statistically significant

• the results are not statistically significant

• there is no difference

• there is a difference

Statistically significant means...

• the research result was unlikely to have occurred by chance

• the research finding was likely to occur by chance

• the research findings is not important

• the research findings is of practical importance