PSYCH 316 Unit 1 (Ch.1-5)

∑X2 + 47 instructs you to _____. A. Square each score and add 47 to it, then sum those numbers B. Square each score add up the squared scores, then add 47 to that sum C. Add 47 to each score, square the result, and sum those numbers D. Add up the scores, square that sum, and add 47 to it

B. Square each score add up the squared scores, then add 47 to that sum

A z-score of z = +1.00 indicates a position in a distribution _____. A.above the mean by 1 point B. above the mean by a distance equal to 1 standard deviation C. belowthemeanby1point D. below the mean by a distance equal to 1 standard deviation

B. above the mean by a distance equal to 1 standard deviation

A distribution of scores shows the mean = 31 and the median = 43. This distribution is probably _____. A. positivelyskewed B. negativelyskewed C. bimodal D. open-ended

B. negativelyskewed

The standard deviation measures the _____. A. sum of squared deviation scores B. Standard distance of a score from the mean C. average deviation of a score from the mean D. average squared distance of a score from the mean

B. standard distance of a score from the mean

A grouped frequency distribution table has categories 0-9, 10-19, 20-29, and 30-39. What is the width of the interval 20-29? A. 9 points B. 9.5 points C. 10 points D. 10.5 points

C. 10 points (29.5 - 19.5 = 10)

For a population with μ = 50 and σ = 10, what is the X value corresponding to z = 0.4? A. 50.4 B. 10 C. 54 D. 10.4

C. 54

A study assess the optimal size (number of other members) for study groups. The variable size of group is _____. A. Discrete and interval B. Continuous and ordinal C. Discrete and ratio D. Continuous and interval

C. Discrete and Ratio

A sample of four scores has SS = 24. What is the variance? A. Thevarianceis6. B. Thevarianceis7. C. The variance is 8. D. The variance is 12.

C. The variance is 8. SS/n-1 = 24/4-1 = 24/3=8

Researchers observed that students' exam scoreswere higher the more sleep they had the night before. This study is _____. A. Descriptive B. Experimental comparison of groups C. Non-experimental group comparison D. Correlational

D. Correlational

A sample of n=12 scores has a mean of M=8. What is the value of ΣX for this sample?

D. ΣX=96

A study assesses the optimal size (number of other members) for study groups. The variable size of group is _____. A. Discrete and interval B. Continuous and ordinal C. Discrete and ratio D. Continuous and interval

Discrete and ratio

• T/F - A biased statistic has been influenced by researcher error.

False - Bias refers to the systematic effect of using sample data to estimate a population parameter

T/F - Variables that cannot be measured directly cannot be studied scientifically

False - Constructs (interval states) can only be observedindirectly, but can be operationally measured

T/F - It would be correct to use a histogram to graph parental marital status data (single, married, divorced...) from a treatment center for children.

False - Marital status is a nominal variable; a bar graph is required

All research methods can show cause-and-effect relationships

False - Only experiments control the influence of participants and environmental variables

T/F - You can determine how many individuals had each score from a grouped frequency distribution.

False - Only the number of individuals in the class interval is available once the scores are grouped

T/F - A score close to the mean has a z-score close to 1.00

False - Scores quite close to the mean have z-scores close to 0.00

T/F - The computational and definitional formulas for SS sometimes give different results.

False - The computational formula is just an algebraic rearrangement of the definitional formula. Results are identical.

T/F - The mean uses all of the scores in the data, so it is the best measure of central tendency for skewed data.

False - The mean will be moved toward the long tail in skewed data so may not be at all representative of the "middle"

T/F - It is possible for more than 50% of the scores in a distribution to have values above the median.

False - The median is defined as the score that divides the distribution exactly in half—50% above/below

T/F - If a sample of n = 10 scores is transformed into z-scores, there will be five positive z-scores and five negative z-scores.

False - The number of z-scores above/below the mean will be exactly the same as the number of original scores above/below the mean

T/F - If all the scores in a data set are the same, the standard deviation is equal to 1.00.

False - When all the scores are the same, they are all equal to the mean. Their deviations = 0, as is their standard deviation.

T/F ∑X2 = (∑X)2

False - When the operations are performed in a different order, the results will be different

T/F - The standard deviation is the distance from the mean to the farthest point on the distribution curve.

False The standard deviation extends from the mean approximately halfway to the most extreme score

T/F - Any frequency distribution is suitable for a stem and leaf display.

False- A stem and leaf display is a simple alternative for a grouped frequency distribution

T/F Variables that cannot be measured directly cannot be studied scientifically

False- Constructs (interval states) can only be observed indirectly, but can be operationally measured

T/F - All research methods have an independent variable

False- Correlational methods do not need an independent variable

T/F - If μ = 40 and 50 corresponds to z = +2.00, then σ = 10 points.

False- If z = +2, then 2σ = 10, so σ = 5

T/F - If σ = 20, a score above the mean by 10 points will have z = 1.00

False- If σ = 20, then z = 10/20 = 0.5

T/F When sample differs from the population there is a systematic difference between groups

False- Sampling error due to random influence may produce unsystematic group difference

T/F - On average, an unbiased sample statistic has the same value as the population parameter.

True - Each sample's statistic differs from the population parameter, but the average of all samples will equal the parameter

• T/F - It is possible for more than 50% of the scores in a distribution to have values above the mean.

True - More than 50% of the scores in a negatively skewed distribution will be above the mean

T/F - Research measurements are made using specific procedures that define constructs

True - Operational definitions assure consistent measurement and provide construct definitions

T/F - A score of 54 is displayed as 5 (stem) and 4 (leaf) in a stem and leaf display.

True - The first digit (5) is the stem and the last digit (4) is the leaf

T/F - Transforming an entire distribution of scores into z-scores will not change the shape of the distribution.

True - The location of each score relative to all other scores is unchanged, so the shape of the distribution is unchanged

T/F - You can determine how many individuals had each score from a frequency distribution table.

True - The original scores can be recreated from the frequency distribution table

T/F - It would be correct to use a histogram to graph the time children spent playing with other children from data collected in a children's treatment center.

True - Time is measured continuously and is an interval variable

T/F - If the mean and median have the same values, the distribution is probably symmetrical.

True - When mean and median are the same, the distribution has to be symmetrical (balanced about M; 50% above/below)

T/F - A sample systematically has less variability than a population.

True Extreme scores affect variability, but are less likely to be included in a sample

T/F Research measurements are made using specific procedures that define constructs

True- Operational definitions assure consistent measurement and provide construct definitions

T/F - A negative z-score always indicates a location below the mean

True- The sign indicates that score is below the mean

T/F (∑X) • (∑X) = (∑X)2

True- This is the definition of (∑X)2

T/F Most research studies data from samples

True-Samples used because it is not feasible or possible to measure all individuals in the population

A researcher is interested in the effect of amount of sleep on high school students' exam scores. Agroup of 75 high school boys agree to participate in the study. The boys are _____. A. A statistic B. A variable C. A parameter D. A sample

a sample

A population has μ = 6 and σ = 2. Each score ismultiplied by 10. What is the shape of the resulting distribution? μ = 60 and σ = 2 μ = 6 and σ = 20 μ = 60 and σ = 20 μ = 6 and σ = 5

μ = 60 and σ = 20 (Multiplying each score by a constant - The mean is changed - The standard deviation is also changed - The standard deviation is multiplied by that constant)