Business Statistics Part 2

What is the mean for the scores shown in the frequency distribution? Value 1 2 3 4 5 Frequency 1 3. 3 2 1

2,9

What is the mean for the following scores: 2, 5, 4, 1, 8?

4

What is the median for the following scores: 2, 5, 4, 1, 8?

4

Suppose the correlation between height and weight for adults is +0.80. What proportion of the variability in weight can be explained by the relationship with height?

64%

A researcher is curious about the IQ of students at the Utrecht University. The entire group students is an example of a:

Population

A set of scores is presented in a histogram. The histogram shows a series of bars that tend to decrease in height from left to right. What is the shape of the distribution?

Positively skewed

In a 500m speed skating race, time results would be considered an example of which level of measurement?

Ratio

What is the correct decision in a hypothesis if the data produce a t-statistic that is in the critical region?

Reject H0

Which of the following assumptions are required if an independent t-test is to be used?

Samples are drawn from a normally distributed population. Homogeneity of variances (equal variances).. The data are either interval or ratio scales. (All the above assumptions (A, B and C) are required.)

IQ tests are standardized so that the mean score is 100 for the entire group of people who take the test. However, if you select a group of 50 who took the test, you probably would not get 100. What statistical concept explains the difference between the two means?

Sampling error

The median is always:

The middle score when results are ranked in order of magnitude

When does a researcher risk a Type I error?

Anytime H0 is rejected.

The seminar rooms in the library are identified by the letters A to H. A researcher records the number of classes held in each room during the first semester. What kind of graph would be appropriate to present the frequency distributions of these data?

Bar chart

Normally distributed data are normally referred to as:

Bell-shaped

What is the null hypothesis for a Chi-square test?

Both variables are independent.

A population has a μ=50 and σ=10. If these scores are transformed into z-scores, the population of z-scores will have a mean and standard deviation of:

μ=0 and σ=1

A population has a mean of μ=35 and a standard deviation of σ=5. After 3 points are added to every score in the population, what are the new values for the mean and standard deviation?

μ=38 and σ=5

If the scores on a test have a mean of 26 and a standard deviation of 4, what is the z-score for a score of 18?

-2

Suppose you wanted to apply a one-tailed test as opposed to a two-tailed test. How would you covert a significance of p = .284?

.284/2=.142

What is varience of for the following set of scores: 2, 2, 2, 2, 2.

0

Which of the following sets of scores has the greatest variability ( range)? A. 2, 5, 8, 11 B. 13, 13, 13, 13 C. 20, 25, 26 ,27 D. 42, 43, 44, 45

A. 2, 5, 8, 11

A Pearson correlation of r=-0.6 indicates

An increase in X is accompanied by a decrease in Y; the relationship is moderate.

What does ANOVA stand for?

Analysis of variance.

Statistical techniques that summarize and organize the data are classified as:

Descriptive statistics

A researchers studies the factors that determine the number of children future couples decide to have. The variable 'number of children' is a :

Discrete variable

Five-point Likert scales (strongly disagree, disagree, neutral, agree, strongly agree) are frequently used to measure motivations and attitudes. A Likert scale is a:

Discrete variable. Ordinal variable. Categorical variable (All of above)

If a researcher sets a level of significance at .05 (i.e. 5%), what does this mean?

Five times out of 100, a significant result will be found that is due to chance alone and not to true relationship.

Which statistical test is used to identify whether there is a relationship between two categorical variables?

Pearson's Chi-square test.

In a linear regression equation, what does a slope of 2.5 indicate?

For every increase of 1.00 on the x-axis, there is an increase of 2.5 on the y-axis.

A sports psychologist was interested in the effects of a six-week imagery intervention on an athlete's ability to execute a sport-specific skills such penalty taking in football. How might you define the imagery variable?

Independent variable

In order for accurate measures of the linear relationship between two variables to be achieved, what type of data are required if using Pearson's correlation coefficient?

Interval

A teacher asks students to identity their favorite reality television show. What type of measurement scale do the different television shows make up?

Nominal

A scatterplot shows:

Scores on one variable plotted against scores on a second variable.

What is a definition of the standard error?

Standard deviation of sample means.

Take the formula Z = (X - μ)/σ, where μ is the mean of the population, X is the value of the element, Z is the z-score and σ is the standard deviation. What does this formula calculate?

Standard score.

A researcher is interested in the travel time of Utrecht University students to college. A group of 50 students is interviewed. Their mean travel time in 16.7 minutes. For this study the mean of 16.7 minutes is an example of a(n)

Statistic

A research report summarizes the results of a t-test by stating: t(35)=5.2, p<0.05. Which of the following is a correct interpretation of this report?

The H0 was rejected and the probability of a Type I error is less than .05.

Which of following statements is the most accurate description for the concept of standard deviation?

The average distance between a score and the mean.

R2 is the notation for:

The coefficient of determination.

What effect would increasing the sample size have on a confidence interval?

The confidence interval would decrease in size.

A teacher gave a statistics test to a class of Geography students and computed the measures of central tendency for the test scores. Which of the following statements cannot be an accurate description of the scores?

The majority of students had scores above the median.

In a linear regression equation, Y=a + bX, what is the b denote?

The regression coefficient, the slope of the line.

If all possible samples of size n=30 are selected from a population with μ=80 and σ=10 and the mean is computed for each sample, then what shape is expected for the distribution of sample means?

The sample means tend to form a normal-shaped distribution whether the population is normal or not.

What does the statistic Cramer's V indicate?

The strength of association between two categorical variables.

How does the shape of the t distribution compare to the normal distribution?

The t distribution is flatter and more spread out, especially when n is small.

Which of the following statements about the t-statistic in regression analysis is not true?

The t-statistic is equal to the regression coefficient divided by its standard deviation.

In an independent t-test output of SPSS, the Levene's test result is p = .006. What can we infer from this number?

The variances of both groups are assumed to be equal.

Which of the following is true about a 95% confidence interval of the mean of a given

There is a 95% chance that the population mean will fall within the limits of the confidence interval.

What kind of variables would you crosstabulate?

Two or more categorical.

Of the following Z-score values, which one represents the location closest to the mean?

Z=-0.3