Suppose you are undertaking a study to investigate the effect of watching the television on the reading scores among Grade 3 school children in Nairobi. You take a random sample of 125 Grade 3 school children in Nairobi and measure how many hours of television each of them watched per week during a school year and their reading scores. Which variable would you put on the horizontal axis of a scatterplot of the data?

Select one:

Reading score, because it is the dependent variable.

Hours of television, because it is the dependent variable.

Reading score, because it is the independent variable.

Hours of television, because it is the independent variable.

Question Two

Which of the following is a true statement?

Select one:

The area under the standard normal curve between 0 and 2 is twice the area between 0 and 1.

For the standard normal curve, the area to the left of 0.1 is the same as the area to the right of 0.9.

The area under the standard normal curve between 0 and 2 is half the area between -2 and 2

For the standard normal curve, 95 percent of the distribution lies within about three standard deviations on each side of the mean.

Question 3

Which of the following statements about the correlation coefficient are true?

Select one:

When we find no correlation between two variables we are advised to regress the variables to assess cause-and-effect relationship.

The correlation coefficient and the slope of the regression line may have opposite signs.

A correlation of 1 indicates a perfect cause-and-effect relationship between the variables.

Correlations of +0.78 and -0.78 indicate the same degree of clustering around the regression line.

Question 4

An airline claims that the mean flights time between Nairobi and Mombasa is 45 minutes. After taking many flights, a local business group believes that the claim is unrealistic and that the actual mean flight time is greater than 45 minutes. If the group conducts a study to investigate its belief, which of the following hypotheses should be tested?

Select one:

H0:sample mean=45 versus H1: sample mean is not equal to 45

H0:sample mean=45 versus H1: sample mean is greater than 45

H0: population mean=45 versus H1: population mean is not equal to 45

H0: population mean=45 versus H1: population mean is greater than 45

Question 5

Mary conducted a study on child development. She measured the age (in months) at which a child begins to talk and also the child's score on an ability test given several years later. The research question is whether the age at which a child talks helps predict the later test score. The least-squares regression line of test score on age is Y=100-1.5X. Using this regression equation, what happens (on average) each month a child delays speech?

Select one:

The test score goes down 100 points.

The test score decreases to 98.5.

The test score goes up by 1.5 points.

The test score goes down by 1.5 points.

Question 6

Individuals who listen to music whilst revising will achieve significantly higher exam grades than will individuals who do their revision in silence. Thinking about this research hypothesis, which of the below would be an appropriate null hypothesis?

Select one:

Individuals who listen to music whilst revising for their exam will achieve significantly lower exam grades than will individuals who revise in silence.

The more music an individual listens to when they are revising, the higher their exam grade will be. In addition, the more silence an individual experiences whilst revising, the lower their exam grade will be.

There will be no difference in exam grade between those individuals who revise whilst listening to music and those individuals who revise in silence. Any observed differences are due to chance alone.

There will be no relationship between examination grade and the amount of music or silence experienced during revision. Any observed relationship is the product of chance alone.

Question 7

Which of the following are true statements?

Select one:

We can always use the absolute values of the calculated statistic to know whether it falls in the critical region or otherwise.

Whether to use a one- or two-sided test is typically decided after the data are gathered.

If there is sufficient evidence to reject a null hypothesis at the 10% level, then there is sufficient evidence to reject it at the 5% level.

If a hypothesis test is conducted at the 1% level, there is a 1% chance of rejecting a true null hypothesis.

Question 8

The central limit theorem refers to which of the following characteristic of the sampling distribution of the sample mean?

Select one:

As you take larger and larger samples from a normally distributed population, the mean of the sampling distribution of the sample mean gets closer and closer to the population mean.

Regardless of the shape of the population's distribution, the sampling distribution of the sample mean from sufficiently large samples will be approximately normally distributed.

Regardless of the shape of the population's distribution, the standard deviation of the sampling distribution of the sample mean from sufficiently large samples will be standard deviation divided by square root of sample size.

As you take larger and larger samples from a normally distributed population, the standard deviation of the sampling distribution of the sample mean gets smaller and smaller.

Question 9

Considering the sample statistic, if the mean of the sampling distribution is equal to the population mean the sample statistic is classified as

Select one:

The unbiased estimator

Hypothetical estimator

Interval estimator

Biased estimator

Question 10

Let X be a random variable that has a skewed distribution with mean and standard deviation equal to 15 and 5, respectively. Based on random samples of size 400, the sampling distribution of the sample mean is

Select one:

approximately normal with mean 15 and standard deviation 5

highly skewed with mean 15 and standard deviation 0.25

approximately normal with mean 15 and standard deviation 0.25

equally skewed with mean 15 and standard deviation 5

pur-new-sol

Related Questions