2ND SEM MIDTERMS (PSYCH STATS)

Question 1

tells whether the score is located above (+) or below (-) the mean

Answer 1

sign

Question 2

tells the distance between the score and the mean in terms of the number of standard deviations.

standardize entire distribution

Answer 2

number

Question 3

specifies the precise location of each X value within a distribution. The numerical value of it specifies the distance from the mean by counting the number of standard deviations between X and m.

provide an objective method for determining how well a specific score represents its population

Answer 3

z-score

Question 4

composed of scores that have been transformed to create predetermined values for m and s. Are used to make dissimilar distributions comparable.

Answer 4

standardized distribution

Question 5

PROPERTIES OF DISTRIBUTION OF Z-SCORES

Answer 5

1. Shape- The distribution of z-scores will have exactly the same shape as the
   original distribution of scores
2. Mean- The z-score distribution will always have a mean of zero
3. Standard Deviation- The distribution of z-scores will always have a standard deviation of s = 1

Question 6

the____ for any specific outcome is defined as a fraction or a proportion of all the possible outcomes.

Answer 6

probability

Question 7

requires that each individual in the population has an equal chance of being selected

Answer 7

Random sampling

sample obtained: simple random sample

Question 8

requires that each individual has an equal chance of being selected and that the probability of being selected stays constant from one selection to the next if more than one individual is selected

Answer 8

Independent random sampling

sample obtained: independent random sample

Question 9

the percentage of individuals with scores at or below a particular X value

Answer 9

Percentile rank

Question 10

the collection of sample means for all the possible random samples of a particular size (n) that can be obtained from a population.

Answer 10

distribution of sample means

Question 11

a distribution of statistics obtained by selecting all the possible samples of a specific size from a population

Answer 11

sampling distribution

Question 12

For any population with mean m and standard deviation s, the distribution of sample means for sample size n will have a mean of m and a standard deviation of s/√n and will approach a normal distribution as n approaches infinity.

Answer 12

Central limit theorem

Question 13

The mean of the distribution of sample means is equal to the mean of the population of scores, m, and is called the

Answer 13

expected value of M

Question 14

The standard deviation of the distribution of sample means, sM. It provides a measure of how much distance is expected on average between a sample mean (M) and the population mean (m).

Answer 14

standard error of M

Question 15

states that the larger the sample size (n), the more probable it is that the sample mean will be close to the population mean.

Answer 15

law of large numbers

Question 16

a statistical method that uses sample data to evaluate a hypothesis about a population.

Answer 16

Hypothesis testing

Question 17

states that in the general population there is no change, no difference, or no relationship. In the context of an experiment, it predicts that the independent variable (treatment) has no effect on the dependent variable (scores) for the population

Answer 17

null hypothesis (H0)

Question 18

states that there is a change, a difference, or a relationship for the general population. In the context of an experiment, it predicts that the independent variable (treatment) does have an effect on the dependent variable.

Answer 18

alternative hypothesis (H1)

Question 19

or the level of significance, is a probability value that is used to define the concept of “very unlikely” in a hypothesis test.

Answer 19

alpha level

Question 20

composed of the extreme sample values that are very unlikely (as defined by the alpha level) to be obtained if the null hypothesis is true. The boundaries for it are determined by the alpha level. If sample data fall in the it, the null hypothesis is rejected.

Answer 20

critical region

Question 21

error occurs when a researcher rejects a null hypothesis that is actually true. In a typical research situation, a Type I error means the researcher concludes that there is evidence for a treatment effect when in fact the treatment has no effect.

Answer 21

Type I

Question 22

occurs when a researcher fails to reject a null hypothesis that is in fact false. In a typical research situation, it means that the hypothesis test has failed to detect a real treatment effect.

Answer 22

Type II error

Question 23

A result that is very unlikely to occur when the null hypothesis is true. That is, the result is sufficient to reject the null hypothesis. Thus, a treatment has a significant effect if the decision from the
hypothesis test is to reject H0.

Answer 23

significant or statistically significant

Question 24

the** statistical hypotheses** (H0 and H1) specify either an increase or a decrease in the population mean. That is, they make a statement about the direction of the effect

Answer 24

directional hypothesis test, or one-tailed test

Question 25

intended to **provide a measurement of the absolute magnitude of a treatment effect**, independent of the size of the sample(s) being used.

Answer 25

effect size

Question 26

statistical test of it is the probability that the **test will correctly reject a false null hypothesis**. That is, the probability that the test will identify a treatment effect if one really exists

Answer 26

power

Question 27

It is computed from the sample variance or sample standard deviation and provides an **estimate of the standard distance** between a *sample mean M and the population mean m.*

Answer 27

estimated standard error (sM)

Question 28

used to test **hypotheses about an unknown population mean**, m, when the *value of s is unknown*. The formula for the it has the same structure as the z-score formula, except that it uses the estimated standard error in the denominator

Answer 28

t statistic

Question 29

describe the number of scores in a **sample that are independent and free to vary**. Because the sample mean places a restriction on the value of one score in the sample, there are n -1 of it for a sample with n scores

Answer 29

Degrees of freedom

Question 30

the **complete set of t values computed for every possible random sample** for a specific sample size (n) or a specific degrees of freedom (df). It approximates the shape of a normal distribution

Answer 30

t distribution

Question 31

an **interval, or range of values centered around a sample statistic**. The logic behind it is that a sample statistic, such as a sample mean, should be relatively near to the corresponding population parameter. Therefore, we can confidently estimate that the value of the parameter should be located in the interval near to the statistic.

Answer 31

confidence interval

Question 32

A **research design** that uses a **separate group of participants for each treatment condition** (or for each population) is called an

Answer 32

independent-measures research design or between-subjects design

Question 33

**research design** that **uses the same group of individuals in all of the different treatment conditions** is called a

Answer 33

repeated-measures design or within-subjects design.

Question 34

each individual in **one sample is matched with an individual in the other sample**. The matching is done so that the two individuals are equivalent (or nearly equivalent) with respect to a specific variable (or variables) that the researcher would like to control.

Answer 34

matched-subjects design