Question

Researchers measured the cholesterol levels in mg per 100 mL for 50 participants. The participants were randomly selected from two age groups: under 50 years, or 50+ years.

1. What is the variable of interest being measured?

2. What type of sampling method is being used here?

3. Are there any possible confounding variables, or other sources of variability?

The 50 participants are asked to change their diet to measure the effect it may have on lowering cholesterol levels. The researchers performing the study offer two dietary options: (1) a diet low in saturated fat, and (2) a diet low in sugar. The participants in the study may chose which diet they prefer to follow. Their cholesterol levels after dieting are recorded on the page labeled Histogram.

4. What type of study is this?

5. What is wrong with the design of this study?

9. If this study was conducted again, and another sample was measured, would you expect similar results? Why or why not?

10. Discuss the similarities and differences of the Low Fat and Low Sugar data sets. Does one diet seem to result in a lower cholesterol level? Explain your answer using complete sentences.

Low Fat 199 199 201 212 213 215 219 222 225 226 226 229 232 233 235 236 238 238 239 239 241 242 243 248 258 258 265 274 276 277 282 283 319

Low Sugar 200 202 225 226 229 237 238 240 240 245 246 250 253 259 263 263 269

Answer 1

Researchers measured the cholesterol levels in mg per 100 mL for 50 participants. The participants were randomly selected from two age groups: under 50 years, or 50+ years

1. What is the variable of interest being measured?

Variable of interest: cholesterol level

2. What type of sampling method is being used here?

Random sampling.

3. Are there any possible confounding variables, or other sources of variability?

Possible confounding variables may be exercise, food type.

The 50 participants are asked to change their diet to measure the effect it may have on lowering cholesterol levels. The researchers performing the study offer two dietary options: (1) a diet low in saturated fat, and (2) a diet low in sugar. The participants in the study may chose which diet they prefer to follow. Their cholesterol levels after dieting are recorded on the page labeled Histogram.

4. What type of study is this?

Experimental study ( there is intervention on the subjects)

5. What is wrong with the design of this study?

The subjects are not randomly allotted to the groups. Self selection bias is present and is a causing a biased sample